Question 1

What's the difference between CSRF and XSS?

Accepted Answer

CSRF tricks a logged-in user’s browser into sending an unwanted request to a site where the user is already authenticated (the attacker doesn’t need to read the response). XSS (Cross-Site Scripting) injects malicious script into a trusted site so the attacker can run code in the victim’s browser, often allowing data theft or taking actions as the user. In practice, XSS can sometimes be used to bypass CSRF defenses by stealing tokens, so you should prevent both.

Question 2

When should I use CSRF protection?

Accepted Answer

Use CSRF protection for any web app that uses cookies (or other automatic browser credentials) for authentication and has state-changing endpoints (POST/PUT/PATCH/DELETE) such as changing email/password, transferring money, updating shipping addresses, or modifying settings. If your API is used cross-origin and relies on cookies, you still need CSRF defenses. If you use Authorization headers with bearer tokens (not cookies) and don’t allow browsers to automatically attach credentials cross-site, CSRF risk is typically lower—but you must still validate CORS and protect against token theft.

Question 3

How much does CSRF cost?

Accepted Answer

CSRF protection is usually a low direct-cost control because it’s commonly built into web frameworks (e.g., server-side middleware that issues and validates tokens) and modern browsers (SameSite cookies). Costs are mainly engineering time to implement correctly, testing/QA, and potential operational costs if you add a WAF or bot protection. If you use a managed WAF/CDN, pricing depends on request volume and enabled security features, but CSRF itself is not typically billed as a standalone feature.

CSRF

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