GHSA-95wr-3f2v-v2wh: Craft CMS has a host header injection leading to SSRF via resource-js endpoint

The resource-js endpoint in Craft CMS allows unauthenticated requests to proxy remote JavaScript resources. When trustedHosts is not explicitly restricted (default configuration), the application trusts the client-supplied Host header.

This allows an attacker to control the derived baseUrl, which is used in prefix validation inside actionResourceJs(). By supplying a malicious Host header, the attacker can make the server issue arbitrary HTTP requests, leading to Server-Side Request Forgery (SSRF).