Headers Security
high Severity
Free Check

CORS Misconfiguration & Wildcard Audit

Detects overly permissive Access-Control-Allow-Origin headers or null origins that expose authenticated APIs to cross-origin attackers.

Test Your Website for CORS Misconfiguration & Wildcard Audit

Run this check along with 90+ automated tests across your domain.

Why It Matters

A misconfigured CORS policy with Access-Control-Allow-Origin: * alongside credentials allows malicious external websites to read private user data.

How We Check This

We send cross-origin probe requests with spoofed Origin headers (e.g. evil.com, null) and analyze whether the server mirrors the origin.

How to Fix & Implement

Copy-paste configuration blocks tailored for your web server or edge proxy.

nginx snippet
if ($http_origin ~* "^https://(app|admin).example.com$") { add_header Access-Control-Allow-Origin "$http_origin"; }

Frequently Asked Questions

Why is Access-Control-Allow-Origin: * dangerous on authenticated endpoints?

It permits any third-party website visited by a user to query your API and read confidential responses.