CSRF, CORS, and Content Security Policy

React applications live in the browser, where attackers can target the same-origin policy, steal CSRF tokens, exploit misconfigured CORS, or inject malicious scripts. This series explains the three pillars of modern frontend security: preventing Cross-Site Request Forgery with tokens and SameSite cookies, safely configuring Cross-Origin Resource Sharing, and authoring a strict Content Security Policy with nonces to block inline script injection.

These defenses are not optional. In 2026, the browser is the frontline of application security. A single misconfigured CORS header can expose your API to credential theft. A missing CSP nonce can allow an attacker to inject a script tag and exfiltrate session data. This series teaches you why each defense exists, how to implement it in React, and what happens when it fails—with real code examples and common pitfalls.

By the end of these 10 articles, you will understand the same-origin model deeply, implement layered defenses in your React components, configure your backend API safely, and deploy security headers that survive a code review. You'll learn to think like a security engineer: assume nothing is trusted, validate every cross-origin request, and treat inline scripts as a last resort.

Articles in this series​

Articles in this series