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.
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.