@opensourceframework/next-csrf

@opensourceframework/next-csrf

CSRF protection for Next.js applications

This is a maintained fork of the original next-csrf package by Juan Olvera (j0lv3r4). The original package was last updated in April 2023 and has been archived. This fork continues maintenance with updates for Next.js 14-16 support and TypeScript improvements.

Attribution

• Original Author: Juan Olvera
• Original Repository: https://github.com/j0lv3r4/next-csrf
• Original License: MIT

Features

• Synchronizer Token Pattern: Implements CSRF mitigation using the Synchronizer Token Pattern
• Signed Cookies: Optional cookie signing for enhanced security
• Next.js Integration: Works with both Pages Router (API routes, getServerSideProps) and App Router
• TypeScript Support: Full TypeScript support with type definitions
• Customizable: Configurable token keys, error messages, and cookie options

Installation

# npm
npm install @opensourceframework/next-csrf

# yarn
yarn add @opensourceframework/next-csrf

# pnpm
pnpm add @opensourceframework/next-csrf

Quick Start

1. Create a CSRF configuration file

// lib/csrf.ts
import { nextCsrf } from '@opensourceframework/next-csrf';

const { csrf, setup } = nextCsrf({
  // Required: A secret key for signing cookies (use environment variable in production)
  secret: process.env.CSRF_SECRET,
  
  // Optional: Customize the token cookie name (default: 'XSRF-TOKEN')
  tokenKey: 'XSRF-TOKEN',
  
  // Optional: Custom error message (default: 'Invalid CSRF token')
  csrfErrorMessage: 'Invalid CSRF token',
  
  // Optional: Methods to ignore (default: ['GET', 'HEAD', 'OPTIONS'])
  ignoredMethods: ['GET', 'HEAD', 'OPTIONS'],
  
  // Optional: Cookie options
  cookieOptions: {
    httpOnly: true,
    path: '/',
    sameSite: 'lax',
    secure: process.env.NODE_ENV === 'production',
  },
});

export { csrf, setup };

2. Set up tokens on initial page load

For Pages Router:

// pages/login.tsx
import { setup } from '../lib/csrf';

function LoginPage() {
  const handleSubmit = async (event) => {
    event.preventDefault();
    
    const response = await fetch('/api/protected', {
      method: 'POST',
    });
    
    if (response.ok) {
      console.log('Request succeeded with CSRF protection');
    }
  };

  return (
    <form onSubmit={handleSubmit}>
      <button type="submit">Submit</button>
    </form>
  );
}

// Setup CSRF tokens on this page
export const getServerSideProps = setup(async ({ req, res }) => {
  return { props: {} };
});

export default LoginPage;

3. Protect API routes

// pages/api/protected.ts
import { csrf } from '../../lib/csrf';
import type { NextApiRequest, NextApiResponse } from 'next';

const handler = async (req: NextApiRequest, res: NextApiResponse) => {
  return res.status(200).json({ 
    message: 'This API route is protected with CSRF!' 
  });
};

export default csrf(handler);

API Reference

nextCsrf(options)

Creates CSRF middleware functions.

Parameters:

Option	Type	Default	Description
secret	string	-	Secret key for signing cookies. Recommended for production.
tokenKey	string	'XSRF-TOKEN'	Name of the CSRF token cookie.
csrfErrorMessage	string	'Invalid CSRF token'	Error message for invalid tokens.
ignoredMethods	string[]	['GET', 'HEAD', 'OPTIONS']	HTTP methods to skip CSRF validation.
cookieOptions	CookieSerializeOptions	See below	Cookie serialization options.

Default Cookie Options:

{
  httpOnly: true,
  path: '/',
  sameSite: 'lax',
  secure: process.env.NODE_ENV === 'production',
}

Returns:

An object with two middleware functions:

• setup - Middleware to create and set CSRF tokens
• csrf - Middleware to validate CSRF tokens

setup(handler)

Middleware that creates CSRF secret and token cookies.

• Works with both API routes (req, res) and getServerSideProps (context)
• Creates two cookies: csrfSecret and the token cookie (default: XSRF-TOKEN)
• If secret option is provided, the token is signed

csrf(handler)

Middleware that validates CSRF tokens on incoming requests.

• Skips validation for ignored methods (default: GET, HEAD, OPTIONS)
• Validates token against secret
• Verifies signed tokens if secret was provided
• Generates a new token after successful validation

HttpError

Custom error class for CSRF-related HTTP errors.

import { HttpError } from '@opensourceframework/next-csrf';

throw new HttpError(403, 'Custom error message');

Migration from next-csrf

If you're migrating from the original next-csrf package:

1. Update imports

- import { nextCsrf } from 'next-csrf';
+ import { nextCsrf } from '@opensourceframework/next-csrf';

2. Update package.json

- "next-csrf": "^0.2.1"
+ "@opensourceframework/next-csrf": "^0.2.2"

3. No code changes required

The API is fully compatible with the original package.

Security Considerations

• Always use a secret in production: Set secret to a cryptographically secure random string.

• Use HTTPS in production: Set secure: true in cookie options for production environments.

• Regenerate tokens: The middleware automatically regenerates tokens after each validated request.

• Session invalidation: If you change the secret, all existing sessions will be invalidated.

• Cookie settings: The default settings (httpOnly: true, sameSite: 'lax') provide good baseline security.

Compatibility

• Next.js: 12.x, 13.x, 14.x, 15.x, 16.x
• Node.js: 18.x or higher
• TypeScript: 5.x

How It Works

The package implements the Synchronizer Token Pattern:

• Setup Phase: When a user visits a page with CSRF setup, the middleware:

  • Generates a unique CSRF secret
  • Creates a token from the secret
  • Stores both in HTTP-only cookies
  • Optionally signs the token with your secret

• Validation Phase: When a user submits a request:

  • The middleware extracts the token from cookies
  • If signed, it verifies the signature
  • It validates the token against the secret
  • If valid, it generates a new token for the next request

Development

# Install dependencies
pnpm install

# Build the package
pnpm build

# Run tests
pnpm test

# Run tests with coverage
pnpm test:coverage

# Type checking
pnpm typecheck

License

MIT License - See LICENSE for details.

Credits

• Original implementation by Juan Olvera
• Maintained by the OpenSource Framework team

Contributing

Contributions are welcome! Please read the contributing guidelines first.