Introduction

Authentication is the cornerstone of application security, serving as the primary gateway that controls access to your application’s features and data. In the rapidly evolving landscape of vibe coding, where AI tools generate code based on natural language prompts, authentication systems often receive inadequate attention to security details. This oversight can lead to significant vulnerabilities that malicious actors can exploit to gain unauthorized access to user accounts and sensitive information.

According to the OWASP Top 10, broken authentication remains one of the most critical web application security risks. A recent study by Security Boulevard found that applications built with AI coding assistants were 35% more likely to contain authentication vulnerabilities compared to traditionally coded applications. This alarming statistic highlights the importance of understanding and addressing authentication security in vibe-coded applications.

When developers instruct AI to “add user authentication” or “create a login system,” the resulting code often implements basic functionality without incorporating crucial security measures like proper password hashing, protection against brute force attacks, secure session management, or multi-factor authentication options. These omissions create significant security gaps that can compromise the entire application.

This article provides a comprehensive guide to implementing secure authentication in vibe-coded applications built with popular full-stack app builders like Lovable.dev, Bolt.new, Tempo Labs, Base44, and Replit. We’ll examine common authentication vulnerabilities in AI-generated code, demonstrate secure implementation approaches for each platform, and provide practical techniques for enhancing authentication security. By following these practices, you can ensure that your vibe-coded applications maintain robust protection against unauthorized access while still benefiting from the rapid development that AI tools enable.

Common Authentication Vulnerabilities in AI-Generated Code

AI coding assistants typically follow certain patterns when generating authentication systems. Understanding these patterns and their associated vulnerabilities is the first step toward implementing secure authentication.

Weak Password Storage

One of the most common and dangerous vulnerabilities in AI-generated authentication code is inadequate password storage:

// Example of insecure password storage in AI-generated code
const User = mongoose.model('User', new mongoose.Schema({
  email: { type: String, required: true, unique: true },
  password: { type: String, required: true }, // Stored as plain text or with weak hashing
  name: String,
  createdAt: { type: Date, default: Date.now }
}));

// Registration handler
app.post('/register', async (req, res) => {
  try {
    const { email, password, name } = req.body;
    
    // Check if user already exists
    const existingUser = await User.findOne({ email });
    if (existingUser) {
      return res.status(400).json({ message: 'User already exists' });
    }
    
    // Create new user with plain text password or weak hashing
    const user = new User({
      email,
      password, // Plain text password
      name
    });
    
    await user.save();
    res.status(201).json({ message: 'User created successfully' });
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

This approach creates several security risks:

• Passwords stored in plain text can be directly read if the database is compromised
• Even with basic hashing (like MD5 or SHA-1), passwords can be easily cracked using rainbow tables
• No salt is used to protect against precomputed hash attacks
• No work factor to make brute force attacks computationally expensive

Missing Brute Force Protection

AI-generated authentication systems often lack protection against brute force attacks:

// Example of login without brute force protection
app.post('/login', async (req, res) => {
  try {
    const { email, password } = req.body;
    
    // Find user by email
    const user = await User.findOne({ email });
    if (!user) {
      return res.status(400).json({ message: 'Invalid credentials' });
    }
    
    // Check password
    if (user.password !== password) { // Plain text comparison
      return res.status(400).json({ message: 'Invalid credentials' });
    }
    
    // Generate JWT token
    const token = jwt.sign({ userId: user._id }, 'your_jwt_secret', { expiresIn: '1h' });
    
    res.json({ token });
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

This code is vulnerable because:

• No limit on login attempts allows attackers to try unlimited password combinations
• No account lockout mechanism after failed attempts
• No delay between login attempts to slow down automated attacks
• No IP-based restrictions or CAPTCHA for suspicious activity

Insecure Session Management

AI tools often generate code with weak session management practices:

// Example of insecure session management
app.post('/login', (req, res) => {
  const { username, password } = req.body;
  
  // Verify credentials (assuming this works correctly)
  if (isValidUser(username, password)) {
    // Create session with insufficient security
    req.session.user = {
      id: getUserId(username),
      username: username,
      role: getUserRole(username)
    };
    
    // Set cookie with weak configuration
    res.cookie('sessionId', req.session.id, {
      // Missing secure flag
      // Missing httpOnly flag
      // Missing SameSite attribute
      // Excessive expiration time
      expires: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000) // 30 days
    });
    
    res.redirect('/dashboard');
  } else {
    res.render('login', { error: 'Invalid credentials' });
  }
});

The vulnerabilities here include:

• Missing secure flag allows cookies to be transmitted over unencrypted connections
• Missing httpOnly flag makes cookies accessible to JavaScript, enabling XSS attacks
• Missing SameSite attribute increases CSRF vulnerability
• Excessive session duration increases the risk if a session is compromised
• No session regeneration after authentication state changes

Inadequate Input Validation

AI-generated authentication code often lacks proper input validation:

// Example of inadequate input validation
app.post('/register', (req, res) => {
  const { email, password, name } = req.body;
  
  // Missing validation for email format
  // Missing validation for password strength
  // Missing sanitization of inputs
  
  // Create user in database
  db.query(
    'INSERT INTO users (email, password, name) VALUES (?, ?, ?)',
    [email, md5(password), name], // Weak hashing with md5
    (err, result) => {
      if (err) {
        return res.status(500).json({ error: 'Registration failed' });
      }
      res.status(201).json({ message: 'User registered successfully' });
    }
  );
});

This code is problematic because:

• No validation of email format allows invalid emails to be registered
• No password strength requirements permits weak passwords
• No input sanitization increases vulnerability to injection attacks
• Weak hashing algorithm (MD5) is cryptographically broken

Missing Multi-Factor Authentication

AI tools rarely include multi-factor authentication (MFA) in generated code:

// Example of authentication without MFA support
function authenticateUser(email, password) {
  // Find user and verify password
  // No support for additional authentication factors
  // No option for enabling MFA
  // No recovery mechanisms that maintain security
}

This limitation means:

• Applications rely solely on passwords, which can be compromised
• No additional verification layer for high-risk operations
• No protection against credential stuffing attacks
• No compliance with security standards that require MFA

Platform-Specific Authentication Vulnerabilities

Each full-stack app builder has its own patterns of authentication implementation. Let’s examine specific examples from each platform.

Lovable.dev

Lovable.dev integrates with Supabase for authentication, but AI-generated code often misses important security configurations:

// Lovable.dev generated authentication code with Supabase
import { createClient } from '@supabase/supabase-js';

const supabaseUrl = 'https://xyzcompany.supabase.co';
const supabaseKey = 'public-anon-key';

export const supabase = createClient(supabaseUrl, supabaseKey);

// Sign up function
export async function signUp(email, password) {
  const { user, error } = await supabase.auth.signUp({
    email,
    password,
  });
  
  if (error) throw error;
  return user;
}

// Sign in function
export async function signIn(email, password) {
  const { user, error } = await supabase.auth.signInWithPassword({
    email,
    password,
  });
  
  if (error) throw error;
  return user;
}

While Supabase provides secure authentication infrastructure, the AI-generated code often misses:

• Password strength requirements
• Email verification enforcement
• Rate limiting configuration
• MFA setup options
• Proper error handling that doesn’t leak information

Bolt.new

Bolt.new also uses Supabase but may generate code with insufficient security measures:

// Bolt.new generated authentication code
import { createClient, SupabaseClient } from '@supabase/supabase-js';
import { useState } from 'react';

// Initialize Supabase client
const supabase: SupabaseClient = createClient(
  process.env.NEXT_PUBLIC_SUPABASE_URL || '',
  process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY || ''
);

// Authentication component
export function AuthForm() {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  
  const handleSignUp = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError(null);
    
    // No password strength validation
    // No rate limiting for sign-up attempts
    
    const { error } = await supabase.auth.signUp({
      email,
      password,
    });
    
    if (error) setError(error.message);
    setLoading(false);
  };
  
  // Form JSX implementation
}

The issues here include:

• No client-side password strength validation
• No protection against automated sign-up attempts
• Potential information leakage through error messages
• No consideration for account recovery security

Tempo Labs

Tempo Labs may generate custom authentication code with security gaps:

// Tempo Labs generated authentication code
import { useState } from 'react';
import { useRouter } from 'next/router';
import axios from 'axios';

export default function Login() {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [error, setError] = useState('');
  const router = useRouter();
  
  const handleSubmit = async (e) => {
    e.preventDefault();
    
    try {
      // No rate limiting
      // No CSRF protection
      const response = await axios.post('/api/login', { email, password });
      
      // Store token in localStorage (insecure)
      localStorage.setItem('token', response.data.token);
      
      router.push('/dashboard');
    } catch (err) {
      setError('Invalid credentials');
    }
  };
  
  // Form JSX implementation
}

// API route implementation
export default async function handler(req, res) {
  if (req.method !== 'POST') {
    return res.status(405).end();
  }
  
  const { email, password } = req.body;
  
  // Find user in database
  const user = await db.findUserByEmail(email);
  
  if (!user) {
    return res.status(401).json({ message: 'Invalid credentials' });
  }
  
  // Compare password with stored hash
  const passwordMatch = await bcrypt.compare(password, user.password);
  
  if (!passwordMatch) {
    return res.status(401).json({ message: 'Invalid credentials' });
  }
  
  // Generate JWT with weak configuration
  const token = jwt.sign(
    { userId: user.id, email: user.email },
    process.env.JWT_SECRET || 'fallback_secret',
    { expiresIn: '30d' } // Excessive token lifetime
  );
  
  res.status(200).json({ token });
}

The vulnerabilities include:

• Storing authentication tokens in localStorage (vulnerable to XSS)
• No rate limiting for login attempts
• No CSRF protection for authentication endpoints
• Excessive JWT expiration time
• Potential use of a fallback secret if environment variable is missing

Base44

Base44 often generates more bare-bones authentication code with significant security gaps:

// Base44 generated authentication code
const express = require('express');
const router = express.Router();
const crypto = require('crypto');
const jwt = require('jsonwebtoken');

// User model
const User = require('../models/User');

// Register route
router.post('/register', async (req, res) => {
  try {
    const { username, email, password } = req.body;
    
    // Check if user exists
    const existingUser = await User.findOne({ email });
    if (existingUser) {
      return res.status(400).json({ message: 'User already exists' });
    }
    
    // Hash password with weak method
    const hashedPassword = crypto
      .createHash('sha256')
      .update(password)
      .digest('hex');
    
    // Create new user
    const newUser = new User({
      username,
      email,
      password: hashedPassword
    });
    
    await newUser.save();
    
    res.status(201).json({ message: 'User created successfully' });
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

// Login route
router.post('/login', async (req, res) => {
  try {
    const { email, password } = req.body;
    
    // Find user
    const user = await User.findOne({ email });
    if (!user) {
      return res.status(400).json({ message: 'Invalid credentials' });
    }
    
    // Hash password for comparison
    const hashedPassword = crypto
      .createHash('sha256')
      .update(password)
      .digest('hex');
    
    // Compare passwords
    if (user.password !== hashedPassword) {
      return res.status(400).json({ message: 'Invalid credentials' });
    }
    
    // Create token
    const token = jwt.sign(
      { id: user._id },
      'your_jwt_secret',
      { expiresIn: '1d' }
    );
    
    res.json({ token });
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

module.exports = router;

The security issues include:

• Using SHA-256 without salt for password hashing (vulnerable to rainbow table attacks)
• Hardcoded JWT secret
• No rate limiting for authentication attempts
• No account lockout mechanism
• No session management considerations

Replit

Replit’s AI assistant often generates Python authentication code with security weaknesses:

# Replit generated authentication code
from flask import Flask, request, jsonify, session
import hashlib
import uuid

app = Flask(__name__)
app.secret_key = 'your_secret_key_here'  # Hardcoded secret key

# In-memory user database (in a real app, this would be a database)
users = {}

@app.route('/register', methods=['POST'])
def register():
    data = request.get_json()
    username = data.get('username')
    password = data.get('password')
    
    if not username or not password:
        return jsonify({'error': 'Username and password are required'}), 400
    
    if username in users:
        return jsonify({'error': 'Username already exists'}), 400
    
    # Weak password hashing
    hashed_password = hashlib.md5(password.encode()).hexdigest()
    
    # Create user
    user_id = str(uuid.uuid4())
    users[username] = {
        'id': user_id,
        'username': username,
        'password': hashed_password
    }
    
    return jsonify({'message': 'User registered successfully'}), 201

@app.route('/login', methods=['POST'])
def login():
    data = request.get_json()
    username = data.get('username')
    password = data.get('password')
    
    if not username or not password:
        return jsonify({'error': 'Username and password are required'}), 400
    
    if username not in users:
        return jsonify({'error': 'Invalid credentials'}), 401
    
    # Weak password hashing
    hashed_password = hashlib.md5(password.encode()).hexdigest()
    
    if users[username]['password'] != hashed_password:
        return jsonify({'error': 'Invalid credentials'}), 401
    
    # Set session
    session['user_id'] = users[username]['id']
    
    return jsonify({'message': 'Login successful'}), 200

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080, debug=True)  # Debug mode enabled in production

The vulnerabilities include:

• Using MD5 for password hashing (cryptographically broken)
• Hardcoded secret key
• In-memory user storage (in this example)
• No rate limiting or brute force protection
• Debug mode enabled in production
• No secure cookie configuration

Secure Authentication Implementation Across Platforms

Now that we’ve identified common vulnerabilities, let’s explore secure authentication implementations for each platform.

Secure Password Storage

The foundation of secure authentication is proper password storage using modern hashing algorithms:

// Secure password hashing with bcrypt
const bcrypt = require('bcrypt');

async function hashPassword(password) {
  // Generate a salt with appropriate cost factor (higher is more secure but slower)
  const salt = await bcrypt.genSalt(12);
  
  // Hash the password with the salt
  const hashedPassword = await bcrypt.hash(password, salt);
  
  return hashedPassword;
}

async function verifyPassword(plainPassword, hashedPassword) {
  // Compare the provided password with the stored hash
  const isMatch = await bcrypt.compare(plainPassword, hashedPassword);
  
  return isMatch;
}

Benefits of this approach:

• Bcrypt automatically incorporates salt to protect against rainbow table attacks
• The work factor (12 in this example) makes brute force attacks computationally expensive
• The salt is different for each password, so identical passwords have different hashes
• Bcrypt is specifically designed for password hashing and is resistant to hardware acceleration

Brute Force Protection

Implementing rate limiting and account lockout mechanisms is essential for preventing brute force attacks:

// Rate limiting middleware using Express Rate Limit
const rateLimit = require('express-rate-limit');
const { RateLimiterMongo } = require('rate-limiter-flexible');
const mongoose = require('mongoose');

// Simple IP-based rate limiting
const loginLimiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // 5 attempts per window
  standardHeaders: true,
  legacyHeaders: false,
  message: 'Too many login attempts, please try again after 15 minutes'
});

// More advanced rate limiting with MongoDB
const mongoConn = mongoose.connection;

const rateLimiterMongo = new RateLimiterMongo({
  storeClient: mongoConn,
  keyPrefix: 'login_fail',
  points: 5, // 5 attempts
  duration: 60 * 15, // 15 minutes
  blockDuration: 60 * 60, // 1 hour block after too many attempts
});

// Middleware for advanced rate limiting
async function rateLimiterMiddleware(req, res, next) {
  const key = req.ip;
  
  try {
    await rateLimiterMongo.consume(key);
    next();
  } catch (error) {
    if (error.remainingPoints <= 0) {
      res.status(429).json({
        message: 'Too many login attempts, please try again later'
      });
    } else {
      res.set('Retry-After', error.msBeforeNext / 1000);
      res.status(429).json({
        message: `Too many login attempts. ${error.remainingPoints} attempts left.`
      });
    }
  }
}

// Apply to login route
app.post('/login', loginLimiter, async (req, res) => {
  // Login logic
});

// Or with advanced rate limiting
app.post('/login', rateLimiterMiddleware, async (req, res) => {
  // Login logic
});

This implementation:

• Limits the number of login attempts from a single IP address
• Provides clear feedback about remaining attempts
• Blocks access after too many failed attempts
• Can be extended to track attempts by username as well as IP

Secure Session Management

Proper session management is critical for maintaining authentication security:

// Secure session configuration with Express
const express = require('express');
const session = require('express-session');
const MongoStore = require('connect-mongo');

const app = express();

// Secure session configuration
app.use(session({
  secret: process.env.SESSION_SECRET,
  name: 'sessionId', // Custom cookie name instead of default
  cookie: {
    maxAge: 1000 * 60 * 60 * 4, // 4 hours
    httpOnly: true, // Prevents JavaScript access
    secure: process.env.NODE_ENV === 'production', // Requires HTTPS in production
    sameSite: 'strict' // Prevents CSRF
  },
  resave: false,
  saveUninitialized: false,
  store: MongoStore.create({
    mongoUrl: process.env.MONGODB_URI,
    ttl: 60 * 60 * 4 // 4 hours (matching cookie maxAge)
  })
}));

// Regenerate session on authentication state change
app.post('/login', async (req, res) => {
  // Verify credentials
  
  // Regenerate session to prevent session fixation
  const regenerateSession = () => {
    return new Promise((resolve, reject) => {
      req.session.regenerate((err) => {
        if (err) {
          reject(err);
        } else {
          resolve();
        }
      });
    });
  };
  
  try {
    await regenerateSession();
    
    // Set user data in new session
    req.session.userId = user.id;
    req.session.userRole = user.role;
    
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: 'Session error' });
  }
});

// Secure logout
app.post('/logout', (req, res) => {
  req.session.destroy((err) => {
    if (err) {
      return res.status(500).json({ error: 'Logout failed' });
    }
    
    res.clearCookie('sessionId');
    res.json({ success: true });
  });
});

This implementation:

• Uses environment variables for session secrets
• Sets secure cookie attributes (httpOnly, secure, sameSite)
• Uses a reasonable session timeout
• Stores sessions in a database rather than memory
• Regenerates the session on login to prevent session fixation
• Properly destroys the session on logout

Input Validation and Sanitization

Proper input validation is essential for authentication security:

// Input validation with express-validator
const { body, validationResult } = require('express-validator');

// Registration route with validation
app.post('/register', [
  // Username validation
  body('username')
    .trim()
    .isLength({ min: 3, max: 30 })
    .withMessage('Username must be between 3 and 30 characters')
    .matches(/^[a-zA-Z0-9_]+$/)
    .withMessage('Username can only contain letters, numbers, and underscores'),
  
  // Email validation
  body('email')
    .trim()
    .isEmail()
    .withMessage('Must be a valid email address')
    .normalizeEmail(),
  
  // Password validation
  body('password')
    .isLength({ min: 8 })
    .withMessage('Password must be at least 8 characters long')
    .matches(/[a-z]/)
    .withMessage('Password must contain at least one lowercase letter')
    .matches(/[A-Z]/)
    .withMessage('Password must contain at least one uppercase letter')
    .matches(/[0-9]/)
    .withMessage('Password must contain at least one number')
    .matches(/[^a-zA-Z0-9]/)
    .withMessage('Password must contain at least one special character'),
  
  // Password confirmation
  body('confirmPassword')
    .custom((value, { req }) => {
      if (value !== req.body.password) {
        throw new Error('Password confirmation does not match password');
      }
      return true;
    })
], async (req, res) => {
  // Check for validation errors
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }
  
  // Registration logic with validated inputs
});

This implementation:

• Validates username format and length
• Ensures email is properly formatted
• Enforces strong password requirements
• Confirms password matches
• Sanitizes inputs to prevent injection attacks

Multi-Factor Authentication

Implementing MFA adds an essential layer of security:

// Multi-factor authentication with speakeasy
const speakeasy = require('speakeasy');
const QRCode = require('qrcode');

// Generate MFA secret for a user
app.post('/mfa/setup', authenticate, async (req, res) => {
  const { userId } = req.user;
  
  // Generate a secret
  const secret = speakeasy.generateSecret({
    name: `YourApp:${req.user.email}`
  });
  
  // Store the secret in the user's record
  await User.findByIdAndUpdate(userId, {
    mfaSecret: secret.base32,
    mfaEnabled: false // Not enabled until verified
  });
  
  // Generate QR code
  QRCode.toDataURL(secret.otpauth_url, (err, dataUrl) => {
    if (err) {
      return res.status(500).json({ error: 'Could not generate QR code' });
    }
    
    res.json({
      secret: secret.base32,
      qrCode: dataUrl
    });
  });
});

// Verify and enable MFA
app.post('/mfa/verify', authenticate, async (req, res) => {
  const { token } = req.body;
  const { userId } = req.user;
  
  // Get user with MFA secret
  const user = await User.findById(userId);
  
  // Verify the token
  const verified = speakeasy.totp.verify({
    secret: user.mfaSecret,
    encoding: 'base32',
    token
  });
  
  if (!verified) {
    return res.status(400).json({ error: 'Invalid verification code' });
  }
  
  // Enable MFA for the user
  await User.findByIdAndUpdate(userId, {
    mfaEnabled: true
  });
  
  res.json({ success: true });
});

// Login with MFA
app.post('/login', async (req, res) => {
  const { email, password, mfaToken } = req.body;
  
  // Find user
  const user = await User.findOne({ email });
  if (!user) {
    return res.status(401).json({ error: 'Invalid credentials' });
  }
  
  // Verify password
  const validPassword = await bcrypt.compare(password, user.password);
  if (!validPassword) {
    return res.status(401).json({ error: 'Invalid credentials' });
  }
  
  // Check if MFA is enabled
  if (user.mfaEnabled) {
    // If no MFA token provided in initial request
    if (!mfaToken) {
      return res.status(200).json({
        requireMfa: true,
        message: 'Please provide MFA token'
      });
    }
    
    // Verify MFA token
    const verified = speakeasy.totp.verify({
      secret: user.mfaSecret,
      encoding: 'base32',
      token: mfaToken
    });
    
    if (!verified) {
      return res.status(401).json({ error: 'Invalid MFA token' });
    }
  }
  
  // Generate session/token
  // ...
  
  res.json({ success: true, token });
});

This implementation:

• Generates a unique secret for each user
• Creates a QR code for easy setup with authenticator apps
• Verifies the token before enabling MFA
• Handles the two-step login process when MFA is enabled
• Provides appropriate responses at each step

Platform-Specific Secure Authentication Implementations

Let’s look at secure authentication implementations for each full-stack app builder.

Lovable.dev Secure Authentication

Lovable.dev uses Supabase for authentication, which provides a solid foundation. Here’s how to enhance its security:

// Secure Lovable.dev authentication with Supabase
import { createClient } from '@supabase/supabase-js';
import { useState } from 'react';

// Initialize Supabase client
const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL;
const supabaseKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY;
export const supabase = createClient(supabaseUrl, supabaseKey);

// Password strength validation
function isStrongPassword(password) {
  const minLength = 8;
  const hasUpperCase = /[A-Z]/.test(password);
  const hasLowerCase = /[a-z]/.test(password);
  const hasNumbers = /\d/.test(password);
  const hasSpecialChars = /[!@#$%^&*(),.?":{}|<>]/.test(password);
  
  return (
    password.length >= minLength &&
    hasUpperCase &&
    hasLowerCase &&
    hasNumbers &&
    hasSpecialChars
  );
}

// Secure sign-up component
export function SignUp() {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [confirmPassword, setConfirmPassword] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(null);
  const [passwordStrength, setPasswordStrength] = useState({
    isStrong: false,
    message: ''
  });
  
  // Check password strength on change
  const handlePasswordChange = (e) => {
    const newPassword = e.target.value;
    setPassword(newPassword);
    
    if (!newPassword) {
      setPasswordStrength({
        isStrong: false,
        message: ''
      });
      return;
    }
    
    const isStrong = isStrongPassword(newPassword);
    setPasswordStrength({
      isStrong,
      message: isStrong
        ? 'Strong password'
        : 'Password must be at least 8 characters and include uppercase, lowercase, numbers, and special characters'
    });
  };
  
  const handleSignUp = async (e) => {
    e.preventDefault();
    
    // Client-side validation
    if (!email || !password) {
      setError('Email and password are required');
      return;
    }
    
    if (password !== confirmPassword) {
      setError('Passwords do not match');
      return;
    }
    
    if (!passwordStrength.isStrong) {
      setError(passwordStrength.message);
      return;
    }
    
    setLoading(true);
    setError(null);
    
    try {
      // Sign up with email confirmation
      const { error } = await supabase.auth.signUp({
        email,
        password,
        options: {
          emailRedirectTo: `${window.location.origin}/auth/callback`,
        }
      });
      
      if (error) throw error;
      
      // Success message
      alert('Check your email for the confirmation link!');
    } catch (error) {
      setError(error.message);
    } finally {
      setLoading(false);
    }
  };
  
  // Form JSX implementation
}

// Secure sign-in with MFA support
export function SignIn() {
  // Implementation with MFA support using Supabase Auth UI
  return (
    <Auth
      supabaseClient={supabase}
      appearance={{ theme: ThemeSupa }}
      providers={[]}
      redirectTo={`${window.location.origin}/auth/callback`}
    />
  );
}

// Server-side authentication check
export async function getServerSideProps(context) {
  const { req } = context;
  const { user } = await supabase.auth.api.getUserByCookie(req);
  
  if (!user) {
    return {
      redirect: {
        destination: '/login',
        permanent: false,
      },
    };
  }
  
  return {
    props: { user },
  };
}

Key security enhancements:

• Client-side password strength validation
• Password confirmation check
• Email verification requirement
• Server-side authentication verification
• Using Supabase Auth UI for standardized, secure authentication flows

Bolt.new Secure Authentication

Bolt.new also uses Supabase but can be enhanced with additional security measures:

// Secure Bolt.new authentication
import { createClient, SupabaseClient, User } from '@supabase/supabase-js';
import { useState, useEffect } from 'react';
import { useRouter } from 'next/router';

// Initialize Supabase client
const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL || '';
const supabaseKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY || '';
const supabase: SupabaseClient = createClient(supabaseUrl, supabaseKey);

// Authentication hook
export function useAuth() {
  const [user, setUser] = useState<User | null>(null);
  const [loading, setLoading] = useState(true);
  const router = useRouter();
  
  useEffect(() => {
    // Get initial session
    const session = supabase.auth.session();
    setUser(session?.user ?? null);
    setLoading(false);
    
    // Listen for auth changes
    const { data: authListener } = supabase.auth.onAuthStateChange(
      (event, session) => {
        setUser(session?.user ?? null);
        setLoading(false);
        
        // Update auth cookie
        fetch('/api/auth', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ event, session }),
        });
      }
    );
    
    return () => {
      authListener?.unsubscribe();
    };
  }, []);
  
  // Sign out function
  const signOut = async () => {
    await supabase.auth.signOut();
    router.push('/login');
  };
  
  return { user, loading, signOut };
}

// Secure login component
export function Login() {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [passwordVisible, setPasswordVisible] = useState(false);
  const router = useRouter();
  
  // Track failed attempts
  const [attempts, setAttempts] = useState(0);
  const MAX_ATTEMPTS = 5;
  
  const handleLogin = async (e: React.FormEvent) => {
    e.preventDefault();
    
    if (attempts >= MAX_ATTEMPTS) {
      setError('Too many failed attempts. Please try again later.');
      return;
    }
    
    setLoading(true);
    setError(null);
    
    try {
      const { error } = await supabase.auth.signInWithPassword({
        email,
        password,
      });
      
      if (error) throw error;
      
      router.push('/dashboard');
    } catch (error: any) {
      setError(error.message);
      setAttempts(prev => prev + 1);
      
      // If approaching max attempts, show warning
      if (attempts + 1 >= MAX_ATTEMPTS - 1) {
        setError(`Login failed. You have ${MAX_ATTEMPTS - attempts - 1} attempts remaining.`);
      }
    } finally {
      setLoading(false);
    }
  };
  
  // Form JSX implementation with password visibility toggle
}

// Protected route component
export function ProtectedRoute({ children }: { children: React.ReactNode }) {
  const { user, loading } = useAuth();
  const router = useRouter();
  
  useEffect(() => {
    if (!loading && !user) {
      router.push('/login');
    }
  }, [user, loading, router]);
  
  if (loading || !user) {
    return <div>Loading...</div>;
  }
  
  return <>{children}</>;
}

Key security enhancements:

• Authentication state management with proper session handling
• Client-side attempt limiting
• Password visibility toggle for usability
• Protected route component for access control
• Server-side session verification

Tempo Labs Secure Authentication

For Tempo Labs, implementing secure JWT authentication with proper storage:

// Secure Tempo Labs authentication
import { useState, useEffect } from 'react';
import { useRouter } from 'next/router';
import axios from 'axios';
import Cookies from 'js-cookie';

// Auth context for state management
export const AuthContext = createContext();

export function AuthProvider({ children }) {
  const [user, setUser] = useState(null);
  const [loading, setLoading] = useState(true);
  const router = useRouter();
  
  // Check for existing token on mount
  useEffect(() => {
    const checkAuth = async () => {
      const token = Cookies.get('auth_token');
      
      if (token) {
        try {
          // Set default auth header
          axios.defaults.headers.common['Authorization'] = `Bearer ${token}`;
          
          // Verify token with backend
          const { data } = await axios.get('/api/auth/me');
          setUser(data.user);
        } catch (error) {
          // Clear invalid token
          Cookies.remove('auth_token');
          delete axios.defaults.headers.common['Authorization'];
        }
      }
      
      setLoading(false);
    };
    
    checkAuth();
  }, []);
  
  // Login function
  const login = async (email, password) => {
    try {
      const { data } = await axios.post('/api/auth/login', {
        email,
        password
      });
      
      // Store token in httpOnly cookie (set by server)
      axios.defaults.headers.common['Authorization'] = `Bearer ${data.token}`;
      
      // Get user data
      const userResponse = await axios.get('/api/auth/me');
      setUser(userResponse.data.user);
      
      return { success: true };
    } catch (error) {
      return {
        success: false,
        error: error.response?.data?.message || 'Login failed'
      };
    }
  };
  
  // Logout function
  const logout = async () => {
    try {
      await axios.post('/api/auth/logout');
    } catch (error) {
      console.error('Logout error:', error);
    }
    
    // Clear auth state
    setUser(null);
    delete axios.defaults.headers.common['Authorization'];
    router.push('/login');
  };
  
  return (
    <AuthContext.Provider value={{ user, loading, login, logout }}>
      {children}
    </AuthContext.Provider>
  );
}

// Secure login component
export function Login() {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [error, setError] = useState('');
  const [loading, setLoading] = useState(false);
  const { login } = useContext(AuthContext);
  const router = useRouter();
  
  const handleSubmit = async (e) => {
    e.preventDefault();
    setLoading(true);
    setError('');
    
    const result = await login(email, password);
    
    if (result.success) {
      router.push('/dashboard');
    } else {
      setError(result.error);
      setLoading(false);
    }
  };
  
  // Form JSX implementation
}

// API route for login
export default async function handler(req, res) {
  if (req.method !== 'POST') {
    return res.status(405).end();
  }
  
  try {
    const { email, password } = req.body;
    
    // Find user
    const user = await db.findUserByEmail(email);
    
    if (!user) {
      return res.status(401).json({ message: 'Invalid credentials' });
    }
    
    // Verify password
    const isValid = await bcrypt.compare(password, user.password);
    
    if (!isValid) {
      return res.status(401).json({ message: 'Invalid credentials' });
    }
    
    // Check if MFA is required
    if (user.mfaEnabled) {
      // Handle MFA flow
      return res.status(200).json({
        requireMfa: true,
        userId: user.id
      });
    }
    
    // Generate JWT
    const token = jwt.sign(
      { userId: user.id },
      process.env.JWT_SECRET,
      { expiresIn: '1h' } // Short expiration time
    );
    
    // Set httpOnly cookie
    res.setHeader(
      'Set-Cookie',
      serialize('auth_token', token, {
        httpOnly: true,
        secure: process.env.NODE_ENV === 'production',
        sameSite: 'strict',
        maxAge: 60 * 60, // 1 hour
        path: '/'
      })
    );
    
    res.status(200).json({ token });
  } catch (error) {
    console.error('Login error:', error);
    res.status(500).json({ message: 'Internal server error' });
  }
}

Key security enhancements:

• Storing tokens in httpOnly cookies instead of localStorage
• Short JWT expiration time
• Proper authentication context management
• Server-side token verification
• Support for MFA flow
• Secure cookie settings

Base44 Secure Authentication

For Base44, implementing proper password hashing and authentication flow:

// Secure Base44 authentication
const express = require('express');
const router = express.Router();
const bcrypt = require('bcrypt');
const jwt = require('jsonwebtoken');
const { body, validationResult } = require('express-validator');
const rateLimit = require('express-rate-limit');

// User model
const User = require('../models/User');

// Rate limiting for registration
const registerLimiter = rateLimit({
  windowMs: 60 * 60 * 1000, // 1 hour
  max: 5, // 5 registrations per IP per hour
  message: 'Too many accounts created from this IP, please try again after an hour'
});

// Rate limiting for login
const loginLimiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // 5 attempts per IP per 15 minutes
  message: 'Too many login attempts, please try again after 15 minutes'
});

// Register route with validation
router.post(
  '/register',
  registerLimiter,
  [
    body('username')
      .trim()
      .isLength({ min: 3, max: 30 })
      .withMessage('Username must be between 3 and 30 characters')
      .matches(/^[a-zA-Z0-9_]+$/)
      .withMessage('Username can only contain letters, numbers, and underscores'),
    
    body('email')
      .trim()
      .isEmail()
      .withMessage('Must be a valid email address')
      .normalizeEmail(),
    
    body('password')
      .isLength({ min: 8 })
      .withMessage('Password must be at least 8 characters long')
      .matches(/[a-z]/)
      .withMessage('Password must contain at least one lowercase letter')
      .matches(/[A-Z]/)
      .withMessage('Password must contain at least one uppercase letter')
      .matches(/[0-9]/)
      .withMessage('Password must contain at least one number')
      .matches(/[^a-zA-Z0-9]/)
      .withMessage('Password must contain at least one special character')
  ],
  async (req, res) => {
    // Check for validation errors
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({ errors: errors.array() });
    }
    
    try {
      const { username, email, password } = req.body;
      
      // Check if user exists
      const existingUser = await User.findOne({
        $or: [{ email }, { username }]
      });
      
      if (existingUser) {
        return res.status(400).json({
          message: 'User already exists'
        });
      }
      
      // Hash password with bcrypt
      const salt = await bcrypt.genSalt(12);
      const hashedPassword = await bcrypt.hash(password, salt);
      
      // Create new user
      const newUser = new User({
        username,
        email,
        password: hashedPassword,
        emailVerified: false
      });
      
      await newUser.save();
      
      // Generate verification token
      const verificationToken = jwt.sign(
        { userId: newUser._id },
        process.env.EMAIL_VERIFICATION_SECRET,
        { expiresIn: '1d' }
      );
      
      // Send verification email (implementation omitted)
      // sendVerificationEmail(email, verificationToken);
      
      res.status(201).json({
        message: 'User created successfully. Please check your email to verify your account.'
      });
    } catch (error) {
      console.error('Registration error:', error);
      res.status(500).json({ message: 'Server error' });
    }
  }
);

// Login route with rate limiting
router.post('/login', loginLimiter, async (req, res) => {
  try {
    const { email, password } = req.body;
    
    // Find user
    const user = await User.findOne({ email });
    if (!user) {
      return res.status(401).json({ message: 'Invalid credentials' });
    }
    
    // Check if email is verified
    if (!user.emailVerified) {
      return res.status(401).json({
        message: 'Please verify your email before logging in'
      });
    }
    
    // Compare passwords
    const isMatch = await bcrypt.compare(password, user.password);
    if (!isMatch) {
      // Increment failed login attempts
      user.failedLoginAttempts = (user.failedLoginAttempts || 0) + 1;
      
      // Lock account after 5 failed attempts
      if (user.failedLoginAttempts >= 5) {
        user.accountLocked = true;
        user.lockUntil = Date.now() + 30 * 60 * 1000; // 30 minutes
      }
      
      await user.save();
      
      return res.status(401).json({ message: 'Invalid credentials' });
    }
    
    // Check if account is locked
    if (user.accountLocked && user.lockUntil > Date.now()) {
      const remainingTime = Math.ceil((user.lockUntil - Date.now()) / 1000 / 60);
      return res.status(401).json({
        message: `Account is locked. Try again in ${remainingTime} minutes`
      });
    }
    
    // Reset failed attempts on successful login
    user.failedLoginAttempts = 0;
    user.accountLocked = false;
    user.lockUntil = null;
    await user.save();
    
    // Create token
    const token = jwt.sign(
      { userId: user._id },
      process.env.JWT_SECRET,
      { expiresIn: '1h' }
    );
    
    // Set httpOnly cookie
    res.cookie('token', token, {
      httpOnly: true,
      secure: process.env.NODE_ENV === 'production',
      sameSite: 'strict',
      maxAge: 60 * 60 * 1000 // 1 hour
    });
    
    res.json({
      token,
      user: {
        id: user._id,
        username: user.username,
        email: user.email
      }
    });
  } catch (error) {
    console.error('Login error:', error);
    res.status(500).json({ message: 'Server error' });
  }
});

// Email verification route
router.get('/verify-email/:token', async (req, res) => {
  try {
    const { token } = req.params;
    
    // Verify token
    const decoded = jwt.verify(token, process.env.EMAIL_VERIFICATION_SECRET);
    
    // Update user
    const user = await User.findByIdAndUpdate(
      decoded.userId,
      { emailVerified: true },
      { new: true }
    );
    
    if (!user) {
      return res.status(404).json({ message: 'User not found' });
    }
    
    res.redirect('/login?verified=true');
  } catch (error) {
    console.error('Email verification error:', error);
    res.status(400).json({ message: 'Invalid or expired token' });
  }
});

module.exports = router;

Key security enhancements:

• Proper password hashing with bcrypt
• Input validation and sanitization
• Rate limiting for registration and login
• Email verification requirement
• Account lockout after failed attempts
• Secure cookie settings for token storage
• JWT with reasonable expiration time

Replit Secure Authentication

For Replit, implementing secure authentication in Python:

# Secure Replit authentication
from flask import Flask, request, jsonify, session, make_response
import bcrypt
import jwt
import datetime
import os
import re
from functools import wraps
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

app = Flask(__name__)
app.config['SECRET_KEY'] = os.environ.get('SECRET_KEY', 'fallback_secret_for_development')

# Setup rate limiting
limiter = Limiter(
    app,
    key_func=get_remote_address,
    default_limits=["200 per day", "50 per hour"]
)

# Database connection (using SQLAlchemy in a real app)
from flask_sqlalchemy import SQLAlchemy

app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get('DATABASE_URL', 'sqlite:///users.db')
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

# User model
class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    password = db.Column(db.String(128), nullable=False)
    email_verified = db.Column(db.Boolean, default=False)
    mfa_secret = db.Column(db.String(32), nullable=True)
    mfa_enabled = db.Column(db.Boolean, default=False)
    failed_login_attempts = db.Column(db.Integer, default=0)
    account_locked = db.Column(db.Boolean, default=False)
    lock_until = db.Column(db.DateTime, nullable=True)
    created_at = db.Column(db.DateTime, default=datetime.datetime.utcnow)

# Create tables
with app.app_context():
    db.create_all()

# Token required decorator
def token_required(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        token = None
        
        # Check for token in headers
        if 'Authorization' in request.headers:
            auth_header = request.headers['Authorization']
            if auth_header.startswith('Bearer '):
                token = auth_header.split(' ')[1]
        
        # Check for token in cookies
        if not token:
            token = request.cookies.get('token')
            
        if not token:
            return jsonify({'message': 'Token is missing'}), 401
            
        try:
            # Decode token
            data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
            current_user = User.query.filter_by(id=data['user_id']).first()
        except:
            return jsonify({'message': 'Token is invalid'}), 401
            
        return f(current_user, *args, **kwargs)
    
    return decorated

# Password validation
def is_strong_password(password):
    if len(password) < 8:
        return False, "Password must be at least 8 characters long"
        
    if not re.search(r'[A-Z]', password):
        return False, "Password must contain at least one uppercase letter"
        
    if not re.search(r'[a-z]', password):
        return False, "Password must contain at least one lowercase letter"
        
    if not re.search(r'[0-9]', password):
        return False, "Password must contain at least one number"
        
    if not re.search(r'[^A-Za-z0-9]', password):
        return False, "Password must contain at least one special character"
        
    return True, "Password is strong"

# Registration route with rate limiting
@app.route('/register', methods=['POST'])
@limiter.limit("5 per hour")
def register():
    data = request.get_json()
    
    # Validate required fields
    if not data or not data.get('username') or not data.get('email') or not data.get('password'):
        return jsonify({'message': 'Missing required fields'}), 400
        
    # Check if user exists
    if User.query.filter_by(email=data['email']).first():
        return jsonify({'message': 'User with this email already exists'}), 400
        
    if User.query.filter_by(username=data['username']).first():
        return jsonify({'message': 'Username already taken'}), 400
    
    # Validate password strength
    is_strong, message = is_strong_password(data['password'])
    if not is_strong:
        return jsonify({'message': message}), 400
    
    # Hash password
    hashed_password = bcrypt.hashpw(data['password'].encode('utf-8'), bcrypt.gensalt(12))
    
    # Create new user
    new_user = User(
        username=data['username'],
        email=data['email'],
        password=hashed_password.decode('utf-8'),
        email_verified=False
    )
    
    db.session.add(new_user)
    db.session.commit()
    
    # Generate verification token
    verification_token = jwt.encode(
        {
            'user_id': new_user.id,
            'exp': datetime.datetime.utcnow() + datetime.timedelta(days=1)
        },
        app.config['SECRET_KEY'],
        algorithm='HS256'
    )
    
    # In a real app, send verification email
    # send_verification_email(new_user.email, verification_token)
    
    return jsonify({'message': 'User created successfully. Please verify your email.'}), 201

# Login route with rate limiting
@app.route('/login', methods=['POST'])
@limiter.limit("5 per 15 minute")
def login():
    data = request.get_json()
    
    if not data or not data.get('email') or not data.get('password'):
        return jsonify({'message': 'Missing email or password'}), 400
        
    # Find user
    user = User.query.filter_by(email=data['email']).first()
    
    if not user:
        return jsonify({'message': 'Invalid credentials'}), 401
    
    # Check if account is locked
    if user.account_locked and user.lock_until and user.lock_until > datetime.datetime.utcnow():
        remaining_seconds = (user.lock_until - datetime.datetime.utcnow()).total_seconds()
        remaining_minutes = int(remaining_seconds / 60) + 1
        return jsonify({'message': f'Account is locked. Try again in {remaining_minutes} minutes'}), 401
    
    # Check password
    if not bcrypt.checkpw(data['password'].encode('utf-8'), user.password.encode('utf-8')):
        # Increment failed login attempts
        user.failed_login_attempts += 1
        
        # Lock account after 5 failed attempts
        if user.failed_login_attempts >= 5:
            user.account_locked = True
            user.lock_until = datetime.datetime.utcnow() + datetime.timedelta(minutes=30)
            
        db.session.commit()
        return jsonify({'message': 'Invalid credentials'}), 401
    
    # Check if email is verified
    if not user.email_verified:
        return jsonify({'message': 'Please verify your email before logging in'}), 401
    
    # Reset failed attempts on successful login
    user.failed_login_attempts = 0
    user.account_locked = False
    user.lock_until = None
    db.session.commit()
    
    # Check if MFA is required
    if user.mfa_enabled:
        if not data.get('mfa_token'):
            return jsonify({
                'message': 'MFA token required',
                'require_mfa': True
            }), 200
            
        # Verify MFA token (implementation omitted)
        # if not verify_totp(user.mfa_secret, data['mfa_token']):
        #     return jsonify({'message': 'Invalid MFA token'}), 401
    
    # Generate JWT token
    token = jwt.encode(
        {
            'user_id': user.id,
            'exp': datetime.datetime.utcnow() + datetime.timedelta(hours=1)
        },
        app.config['SECRET_KEY'],
        algorithm='HS256'
    )
    
    # Create response with httpOnly cookie
    response = make_response(jsonify({
        'message': 'Login successful',
        'token': token
    }))
    
    response.set_cookie(
        'token',
        token,
        httponly=True,
        secure=os.environ.get('FLASK_ENV') == 'production',
        samesite='Strict',
        max_age=60*60  # 1 hour
    )
    
    return response

# Protected route example
@app.route('/profile', methods=['GET'])
@token_required
def get_profile(current_user):
    return jsonify({
        'username': current_user.username,
        'email': current_user.email,
        'mfa_enabled': current_user.mfa_enabled
    })

# Email verification route
@app.route('/verify-email/<token>', methods=['GET'])
def verify_email(token):
    try:
        data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
        user = User.query.filter_by(id=data['user_id']).first()
        
        if not user:
            return jsonify({'message': 'User not found'}), 404
            
        user.email_verified = True
        db.session.commit()
        
        return jsonify({'message': 'Email verified successfully'}), 200
    except:
        return jsonify({'message': 'Invalid or expired token'}), 400

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080, debug=False)  # Debug mode disabled in production

Key security enhancements:

• Proper password hashing with bcrypt
• Strong password validation
• Rate limiting for registration and login
• Account lockout mechanism
• Email verification requirement
• Secure cookie settings for token storage
• JWT with reasonable expiration time
• MFA support
• Debug mode disabled in production

Best Practices for Secure Authentication in Vibe Coding

To implement secure authentication in vibe-coded applications, follow these best practices:

1. Use Specific Prompts for Security

When using AI tools to generate authentication code, include security requirements in your prompts:

Instead of:

Create a user authentication system

Use:

Create a secure user authentication system with the following features:
1. Password hashing using bcrypt with a cost factor of 12
2. Input validation for email and password strength
3. Protection against brute force attacks with rate limiting
4. Secure session management with httpOnly cookies
5. Email verification requirement
6. Support for multi-factor authentication

2. Implement Proper Password Storage

Never store passwords in plain text or with weak hashing algorithms:

• Use bcrypt, Argon2, or PBKDF2 for password hashing
• Use a sufficient work factor (cost) to make brute force attacks computationally expensive
• Never use MD5 or SHA-1 for password hashing
• Include a unique salt for each password (built into bcrypt and Argon2)

3. Enforce Strong Password Policies

Require users to create strong passwords:

• Minimum length of 8 characters
• Combination of uppercase and lowercase letters
• Inclusion of numbers and special characters
• Check against common password lists
• Consider implementing a password strength meter

4. Implement Brute Force Protection

Prevent automated attacks on authentication endpoints:

• Implement rate limiting for login attempts
• Add account lockout after multiple failed attempts
• Use exponential backoff for repeated failures
• Consider CAPTCHA for suspicious activity
• Log and alert on unusual authentication patterns

5. Secure Session Management

Properly manage user sessions after authentication:

• Use httpOnly cookies for storing session tokens
• Set the secure flag in production environments
• Use the SameSite attribute to prevent CSRF
• Implement reasonable session timeouts
• Regenerate session IDs after authentication state changes
• Properly invalidate sessions on logout

6. Implement Multi-Factor Authentication

Add an additional layer of security with MFA:

• Offer TOTP (Time-based One-Time Password) authentication
• Consider SMS, email, or push notification options
• Implement secure recovery mechanisms
• Allow users to manage their MFA settings
• Require MFA for sensitive operations

7. Validate and Sanitize Inputs

Prevent injection attacks and other vulnerabilities:

• Validate email format and other user inputs
• Sanitize inputs to prevent XSS and injection attacks
• Use parameterized queries for database operations
• Implement proper error handling that doesn’t leak information

8. Implement Secure Password Reset

Create a secure password reset flow:

• Use time-limited, single-use tokens
• Send reset links to verified email addresses
• Require verification before changing passwords
• Log password changes and notify users
• Don’t reveal account existence through reset flows

Real-World Scenarios and Solutions

Let’s examine some real-world authentication scenarios in vibe-coded applications and their solutions.

Scenario 1: Weak Password Storage

Problem: A developer used vibe coding to create an authentication system that stores passwords with MD5 hashing, which is cryptographically broken.

Solution:

1. Migrate to a secure password hashing algorithm:

   const bcrypt = require('bcrypt');
   
   // Function to migrate user passwords
   async function migrateUserPassword(user) {
     // Check if password needs migration (stored with MD5)
     if (user.passwordVersion !== 'bcrypt') {
       // When user logs in with correct MD5 password
       // Hash their password with bcrypt
       const hashedPassword = await bcrypt.hash(plainTextPassword, 12);
       
       // Update user record
       user.password = hashedPassword;
       user.passwordVersion = 'bcrypt';
       await user.save();
     }
   }
   
   // Update login logic to handle migration
   async function login(email, password) {
     const user = await User.findOne({ email });
     
     if (!user) {
       return { success: false, message: 'Invalid credentials' };
     }
     
     let isValid = false;
     
     // Check if password needs migration
     if (user.passwordVersion !== 'bcrypt') {
       // Verify with old MD5 method
       const md5Hash = crypto
         .createHash('md5')
         .update(password)
         .digest('hex');
       
       isValid = user.password === md5Hash;
       
       // If valid, migrate to bcrypt
       if (isValid) {
         user.password = await bcrypt.hash(password, 12);
         user.passwordVersion = 'bcrypt';
         await user.save();
       }
     } else {
       // Verify with bcrypt
       isValid = await bcrypt.compare(password, user.password);
     }
     
     if (!isValid) {
       return { success: false, message: 'Invalid credentials' };
     }
     
     // Generate token and complete login
     // ...
     
     return { success: true, token };
   }

2. Notify users about the security upgrade and encourage password changes.

Scenario 2: Missing Brute Force Protection

Problem: A vibe-coded authentication system allows unlimited login attempts, making it vulnerable to brute force attacks.

Solution:

1. Implement rate limiting middleware:

   const rateLimit = require('express-rate-limit');
   const RedisStore = require('rate-limit-redis');
   const Redis = require('ioredis');
   
   const redisClient = new Redis({
     host: process.env.REDIS_HOST,
     port: process.env.REDIS_PORT,
     password: process.env.REDIS_PASSWORD
   });
   
   // Global rate limiter
   const globalLimiter = rateLimit({
     windowMs: 15 * 60 * 1000, // 15 minutes
     max: 100, // 100 requests per window
     standardHeaders: true,
     legacyHeaders: false,
     message: 'Too many requests, please try again later',
     store: new RedisStore({
       sendCommand: (...args) => redisClient.call(...args)
     })
   });
   
   // Specific login rate limiter
   const loginLimiter = rateLimit({
     windowMs: 15 * 60 * 1000, // 15 minutes
     max: 5, // 5 login attempts per window
     standardHeaders: true,
     legacyHeaders: false,
     message: 'Too many login attempts, please try again after 15 minutes',
     store: new RedisStore({
       sendCommand: (...args) => redisClient.call(...args),
       prefix: 'rl:login:'
     })
   });
   
   // Apply limiters to routes
   app.use(globalLimiter); // Apply to all routes
   app.post('/login', loginLimiter, loginController); // Apply to login route

2. Implement account-specific lockout:

   // In login controller
   async function login(req, res) {
     const { email, password } = req.body;
     
     // Find user
     const user = await User.findOne({ email });
     
     // Check if account is locked
     if (user && user.accountLocked && user.lockUntil > Date.now()) {
       const remainingTime = Math.ceil((user.lockUntil - Date.now()) / 1000 / 60);
       return res.status(429).json({
         message: `Account is locked. Try again in ${remainingTime} minutes`
       });
     }
     
     // Verify credentials
     if (!user || !await bcrypt.compare(password, user.password)) {
       // If user exists, increment failed attempts
       if (user) {
         user.failedLoginAttempts = (user.failedLoginAttempts || 0) + 1;
         
         // Lock account after 5 failed attempts
         if (user.failedLoginAttempts >= 5) {
           user.accountLocked = true;
           user.lockUntil = Date.now() + 30 * 60 * 1000; // 30 minutes
         }
         
         await user.save();
       }
       
       return res.status(401).json({ message: 'Invalid credentials' });
     }
     
     // Reset failed attempts on successful login
     if (user.failedLoginAttempts > 0) {
       user.failedLoginAttempts = 0;
       user.accountLocked = false;
       user.lockUntil = null;
       await user.save();
     }
     
     // Complete login process
     // ...
   }

Scenario 3: Insecure Session Management

Problem: A vibe-coded application stores authentication tokens in localStorage, making them vulnerable to XSS attacks.

Solution:

1. Switch to httpOnly cookies for token storage:

   // Server-side code
   app.post('/login', async (req, res) => {
     // Verify credentials
     
     // Generate JWT
     const token = jwt.sign(
       { userId: user._id },
       process.env.JWT_SECRET,
       { expiresIn: '1h' }
     );
     
     // Set httpOnly cookie instead of returning token in response
     res.cookie('token', token, {
       httpOnly: true,
       secure: process.env.NODE_ENV === 'production',
       sameSite: 'strict',
       maxAge: 60 * 60 * 1000 // 1 hour
     });
     
     // Return user data without token
     res.json({
       user: {
         id: user._id,
         name: user.name,
         email: user.email
       }
     });
   });
   
   // Client-side code
   async function login(email, password) {
     try {
       const response = await fetch('/login', {
         method: 'POST',
         headers: {
           'Content-Type': 'application/json'
         },
         body: JSON.stringify({ email, password }),
         credentials: 'include' // Important for cookies
       });
       
       const data = await response.json();
       
       if (response.ok) {
         // Store user data in state management
         // No need to store token as it's in the cookie
         return { success: true, user: data.user };
       } else {
         return { success: false, error: data.message };
       }
     } catch (error) {
       return { success: false, error: 'Login failed' };
     }
   }

2. Update authentication middleware to check for cookies:

   function authenticate(req, res, next) {
     const token = req.cookies.token;
     
     if (!token) {
       return res.status(401).json({ message: 'Authentication required' });
     }
     
     try {
       const decoded = jwt.verify(token, process.env.JWT_SECRET);
       req.user = decoded;
       next();
     } catch (error) {
       res.clearCookie('token');
       return res.status(401).json({ message: 'Invalid or expired token' });
     }
   }

Scenario 4: Missing Multi-Factor Authentication

Problem: A vibe-coded authentication system lacks multi-factor authentication, making it vulnerable to credential stuffing attacks.

Solution:

1. Implement TOTP-based MFA:

   const speakeasy = require('speakeasy');
   const QRCode = require('qrcode');
   
   // Setup MFA for a user
   app.post('/mfa/setup', authenticate, async (req, res) => {
     const userId = req.user.userId;
     
     // Generate a secret
     const secret = speakeasy.generateSecret({
       name: `YourApp:${req.user.email}`
     });
     
     // Store the secret in the user's record
     await User.findByIdAndUpdate(userId, {
       mfaSecret: secret.base32,
       mfaEnabled: false // Not enabled until verified
     });
     
     // Generate QR code
     QRCode.toDataURL(secret.otpauth_url, (err, dataUrl) => {
       if (err) {
         return res.status(500).json({ error: 'Could not generate QR code' });
       }
       
       res.json({
         secret: secret.base32,
         qrCode: dataUrl
       });
     });
   });
   
   // Verify and enable MFA
   app.post('/mfa/verify', authenticate, async (req, res) => {
     const { token } = req.body;
     const userId = req.user.userId;
     
     // Get user with MFA secret
     const user = await User.findById(userId);
     
     // Verify the token
     const verified = speakeasy.totp.verify({
       secret: user.mfaSecret,
       encoding: 'base32',
       token,
       window: 1 // Allow 1 period before and after for clock skew
     });
     
     if (!verified) {
       return res.status(400).json({ error: 'Invalid verification code' });
     }
     
     // Enable MFA for the user
     await User.findByIdAndUpdate(userId, {
       mfaEnabled: true
     });
     
     res.json({ success: true });
   });
   
   // Login with MFA
   app.post('/login', async (req, res) => {
     const { email, password, mfaToken } = req.body;
     
     // Find user
     const user = await User.findOne({ email });
     if (!user) {
       return res.status(401).json({ error: 'Invalid credentials' });
     }
     
     // Verify password
     const validPassword = await bcrypt.compare(password, user.password);
     if (!validPassword) {
       return res.status(401).json({ error: 'Invalid credentials' });
     }
     
     // Check if MFA is enabled
     if (user.mfaEnabled) {
       // If no MFA token provided in initial request
       if (!mfaToken) {
         return res.status(200).json({
           requireMfa: true,
           message: 'Please provide MFA token'
         });
       }
       
       // Verify MFA token
       const verified = speakeasy.totp.verify({
         secret: user.mfaSecret,
         encoding: 'base32',
         token: mfaToken,
         window: 1
       });
       
       if (!verified) {
         return res.status(401).json({ error: 'Invalid MFA token' });
       }
     }
     
     // Generate JWT and complete login
     // ...
     
     res.json({ success: true, token });
   });

2. Implement recovery options:

   // Generate recovery codes
   app.post('/mfa/recovery-codes', authenticate, async (req, res) => {
     const userId = req.user.userId;
     
     // Generate 10 random recovery codes
     const recoveryCodes = Array.from({ length: 10 }, () => 
       crypto.randomBytes(4).toString('hex').toUpperCase()
     );
     
     // Hash the recovery codes before storing
     const hashedCodes = await Promise.all(
       recoveryCodes.map(code => bcrypt.hash(code, 10))
     );
     
     // Store hashed codes in user record
     await User.findByIdAndUpdate(userId, {
       mfaRecoveryCodes: hashedCodes
     });
     
     // Return plain text codes to user (only shown once)
     res.json({ recoveryCodes });
   });
   
   // Login with recovery code
   app.post('/login/recovery', async (req, res) => {
     const { email, password, recoveryCode } = req.body;
     
     // Find user
     const user = await User.findOne({ email });
     if (!user) {
       return res.status(401).json({ error: 'Invalid credentials' });
     }
     
     // Verify password
     const validPassword = await bcrypt.compare(password, user.password);
     if (!validPassword) {
       return res.status(401).json({ error: 'Invalid credentials' });
     }
     
     // Verify recovery code
     let validRecoveryCode = false;
     let validCodeIndex = -1;
     
     for (let i = 0; i < user.mfaRecoveryCodes.length; i++) {
       if (await bcrypt.compare(recoveryCode, user.mfaRecoveryCodes[i])) {
         validRecoveryCode = true;
         validCodeIndex = i;
         break;
       }
     }
     
     if (!validRecoveryCode) {
       return res.status(401).json({ error: 'Invalid recovery code' });
     }
     
     // Remove used recovery code
     user.mfaRecoveryCodes.splice(validCodeIndex, 1);
     await user.save();
     
     // Generate JWT and complete login
     // ...
     
     res.json({ 
       success: true, 
       token,
       message: 'Recovery code used. Please set up MFA again.'
     });
   });

Conclusion

Authentication security is a critical aspect of application development that requires careful attention, especially in the context of vibe coding where AI tools may prioritize functionality over security. By understanding common authentication vulnerabilities in AI-generated code and implementing secure alternatives, you can build robust authentication systems that protect your users and their data.

The key principles of secure authentication in vibe-coded applications include:

1. Proper password storage using modern hashing algorithms like bcrypt or Argon2
2. Brute force protection through rate limiting and account lockout mechanisms
3. Secure session management with httpOnly cookies and appropriate security flags
4. Input validation and sanitization to prevent injection attacks
5. Multi-factor authentication to add an additional layer of security
6. Secure password reset flows that don’t leak information

Each full-stack app builder—Lovable.dev, Bolt.new, Tempo Labs, Base44, and Replit—has its own authentication patterns and potential vulnerabilities. By applying platform-specific security enhancements and following best practices, you can ensure that your vibe-coded applications maintain robust authentication security while still benefiting from the rapid development that AI tools enable.

Remember that authentication is your application’s first line of defense. Investing time in securing this critical component will protect your users, your data, and your reputation from the devastating consequences of security breaches.

Additional Resources

• OWASP Authentication Cheat Sheet
• NIST Digital Identity Guidelines
• Have I Been Pwned API (for checking compromised passwords)
• Auth0 MFA Documentation
• Supabase Auth Documentation
• JWT.io (for understanding JWT structure and security)

References

1. OWASP. (2023). “Top 10 Web Application Security Risks.” Retrieved from https://owasp.org/Top10/
2. Security Boulevard. (2025). “AI-Generated Code Security Report.” Retrieved from https://securityboulevard.com/2025/02/ai-generated-code-security-report
3. Checkmarx. (2025). “Security in Vibe Coding: Innovation Meets Risk.” Retrieved from https://checkmarx.com/blog/security-in-vibe-coding/
4. Segura, T. (2025). “A Vibe Coding Security Playbook.” Infisical. Retrieved from https://infisical.com/blog/vibe-coding-security-playbook
5. Trotta, F. (2025). “5 Vibe Coding Risks and Ways to Avoid Them in 2025.” Zencoder. Retrieved from https://zencoder.ai/blog/vibe-coding-risks