A web application firewall sits in front of your site and filters incoming traffic against known attack patterns (SQL injection, cross-site scripting, common exploit signatures) before it reaches your application.
What it protects against
- Known exploit patterns targeting common vulnerabilities
- Basic bot and scraper traffic
- Some volumetric attack traffic, depending on the provider
What it doesn’t replace
A WAF is a mitigating layer, not a substitute for actually fixing vulnerabilities in your own code and dependencies — it reduces exposure while you patch, but shouldn’t be the only line of defense long-term.
Who should use one
Any site handling user accounts, payments, or meaningful traffic volume benefits; many CDN providers now include a basic WAF at little or no extra cost, making adoption relatively low-friction.
FAQ
Can a WAF fully replace patching vulnerable software?
No — it reduces the window of exposure and blocks many known exploit attempts, but an unpatched vulnerability can still eventually be exploited through a pattern the WAF doesn’t recognize.