Broken Authentication in React.js: Fix It Fast

Why Broken Authentication Happens in React

React runs in the browser, so anything you store or trust on the client can be stolen, forged, or replayed. Common pitfalls:

• Tokens in localStorage (easy XSS loot)
• No rate-limiting or MFA on login
• Weak session cookie flags (no HttpOnly, Secure, SameSite)
• DIY route guards that never verify on the server

👉 Use server-side sessions (or hardened JWT), HttpOnly cookies, MFA, and server verification.

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Bad vs Good: Quick Code Diffs

❌ Anti-pattern: store JWT in localStorage

// Attacker with XSS can exfiltrate this
localStorage.setItem('token', jwt);

✅ Prefer HttpOnly session cookies

// React login: cookie managed by browser, not JS
await fetch('/api/login', {
  method: 'POST',
  credentials: 'include',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({ email, password })
});

Server: set a hardened session cookie

// Node/Express example
res.cookie('sid', sessionId, {
  httpOnly: true,
  secure: true,
  sameSite: 'lax',   // or 'strict' for tighter flows
  path: '/',
  maxAge: 60 * 60 * 1000
});

Protect routes with a real server check

// React route guard that verifies on the server
useEffect(() => {
  fetch('/api/me', { credentials: 'include' })
    .then(r => r.ok ? setAuthed(true) : navigate('/login'));
}, []);

Throttle brute force & credential stuffing

// Express: simple rate limit on login
import rateLimit from 'express-rate-limit';
app.post('/api/login',
  rateLimit({ windowMs: 15*60*1000, max: 10 }),
  loginHandler
);

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Minimal Secure Auth Checklist (React + API)

• [ ] HttpOnly, Secure, SameSite cookies for sessions
• [ ] MFA/2FA for risky actions and logins
• [ ] Rate limiting + IP/device fingerprint checks
• [ ] Short-lived sessions + rotation on privilege change
• [ ] CSRF protection (cookies + SameSite, or CSRF token for unsafe methods)
• [ ] Server-side authorization on every API call

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Screenshot of the free tools webpage where you can access security assessment tools.

Try It on Your Project (Free)

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Sample Assessment Report by the tool to check Website Vulnerability

Sample vulnerability assessment report generated with our free tool, providing insights into possible vulnerabilities.

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Deep Dives & How-Tos

• Browse hands-on guides and case studies on our blog: https://www.pentesttesting.com/blog/

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Related Services (Pick What You Need)

Managed IT Services

Harden identity, patching, device control, and IAM policies so broken auth doesn’t creep back in.
https://www.pentesttesting.com/managed-it-services/

AI Application Cybersecurity

Threat-model AI flows (tokens, model gateways, webhooks) and secure auth around ML features.
https://www.pentesttesting.com/ai-application-cybersecurity/

Offer Cybersecurity to Your Clients

Agencies/MSPs: white-label assessments and remediation, including auth hardening playbooks.
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Copy-Paste Snippet: Secure Fetch Wrapper (Bonus)

// Reuse across your app to always send cookies
export const api = (url, opts={}) =>
  fetch(url, {
    credentials: 'include',
    headers: { 'Content-Type': 'application/json', ...(opts.headers||{}) },
    ...opts
  });