Claircore: Unauthenticated attackers can submit manifests with URIs pointing to internal services or cloud metadata endpoints

A flaw was found in Clair. The fetcher component makes outbound HTTP requests to attacker-supplied URIs from manifest layer descriptors without IP or scheme filtering. When PSK authentication is not configured (opt-in, not enforced by default), an unauthenticated attacker can submit a manifest with a URI pointing to internal services or cloud metadata endpoints. The SSRF is reflective for non-200 responses, leaking up to 256 bytes of error body content via CheckResponse error messages. Operator-managed Red Hat Quay deployments auto-configure PSK and are not exposed to the unauthenticated attack vector.