What Is a WAF and Why Does Your Website Need One?

WAF in plain English

A Web Application Firewall sits between the internet and your website, inspecting every HTTP request before it reaches your application. It compares incoming traffic against a ruleset of known attack patterns — SQL injection strings, XSS payloads, path traversal attempts — and blocks the ones that match.

What a WAF blocks

SQL injection (attackers trying to read or modify your database), Cross-Site Scripting (XSS), Remote File Inclusion (RFI), Local File Inclusion (LFI), OS command injection, and known exploit attempts against common vulnerabilities. A well-configured WAF stops the vast majority of automated attacks.

WAF vs vulnerability scanner: what's the difference?

A WAF blocks attacks in real time. A vulnerability scanner like UebGuard finds the weaknesses in your application that a WAF is protecting — and tells you how to eliminate them at the source. You need both: a WAF stops attacks today; a scanner eliminates the vulnerabilities those attacks are targeting.

Do you need a WAF if you're on Cloudflare?

Cloudflare's free WAF offers basic protection. For serious security, Cloudflare's WAF rules require higher plan tiers. More importantly, WAF rules block known patterns — they don't scan your application for the vulnerabilities those patterns exploit.

Which websites need a WAF?

Any website that accepts user input, processes payments, stores user data, or runs on a CMS needs WAF protection. That's essentially every modern website. If you collect an email address in a form, you're a target.