Cross-Site Request Forgery

Cross-Site Request Forgery Overview

Cross-Site Request Forgery is a building block you will reach for often in authentication. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn cross-site request forgery properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real authentication projects.

import express from 'express';
import jwt from 'jsonwebtoken';

const app = express();
app.use(express.json());

function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  try {
    req.user = jwt.verify(token, process.env.JWT_SECRET);
    next();
  } catch {
    res.status(401).json({ error: 'Unauthorized' });
  }
}

Authentication middleware verifies the caller's identity before protected handlers run.

Cross-Site Request Forgery Example

// verify the caller on every protected request
function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  req.user = verifyToken(token); // throws if invalid
  next();
}

• Start from a minimal Cross-Site Request Forgery example and grow it only as needed.
• Keep configuration explicit so Cross-Site Request Forgery behaves the same in every environment.
• Name things clearly so teammates understand your Cross-Site Request Forgery at a glance.
• Add tests around Cross-Site Request Forgery early to lock in expected behaviour.

Authentication Cheatsheet

Quick authentication reference related to cross-site request forgery.

How Cross-Site Request Forgery Works

Cross-Site Request Forgery is part of proving who a user is and what they are allowed to do. Authentication verifies identity, while authorization decides access — and cross-site request forgery plays a specific role in that flow.

Authentication middleware verifies the caller's identity before protected handlers run.

• Never store or log plain-text passwords or secrets.
• Prefer short-lived tokens with refresh over long-lived ones.
• Always send credentials over HTTPS.
• Fail closed: deny access when anything is uncertain.

Security Guidance for Cross-Site Request Forgery

Security is the whole point of cross-site request forgery. Small mistakes — weak hashing, tokens in localStorage, missing rate limits — are exactly what attackers look for, so follow proven defaults.

Common Mistakes

• Skipping error handling and edge cases when wiring up cross-site request forgery.
• Leaving cross-site request forgery untested, so regressions slip into production.
• Over-engineering cross-site request forgery before you actually need the extra flexibility.
• Ignoring documentation, which makes cross-site request forgery hard for the next developer to change.

Key Takeaways

• Cross-Site Request Forgery is a core part of working effectively with authentication.
• Start small and keep cross-site request forgery focused on a single responsibility.
• Apply consistent patterns so cross-site request forgery scales across your project.
• Test and document cross-site request forgery to keep it maintainable over time.