CVE-2026-73432: Stored Server-Side Request Forgery in Remote-Instance Synchronization Allows Access to Internal Services in vulnerability-lookup

Vulnerability-Lookup contains a server-side request forgery (SSRF) vulnerability in the remote-instance synchronization functionality. Remote instance addresses were validated only for basic URL syntax before being stored, while the synchronization worker later dereferenced these addresses using requests.get() with automatic redirect handling and without enforcing network-boundary restrictions.

An authenticated administrator with the admin:access permission could configure a remote instance whose address points to an internal, loopback, link-local, or cloud metadata HTTP(S) service. When synchronization is performed, the Vulnerability-Lookup server would issue the request from its own network context. An attacker could also use a publicly accessible URL that redirects to an internal destination, because redirects were previously followed without revalidating the destination.

Successful exploitation could allow a privileged attacker to probe or interact with services that are accessible from the Vulnerability-Lookup server but not directly reachable by the attacker, including private network services or cloud instance metadata endpoints. The exact confidentiality, integrity, or availability impact depends on the services reachable from the application server.

The patch introduces a shared outbound URL policy that restricts remote instances to HTTP(S), rejects non-public IP addresses, resolves hostnames at request time, and manually validates each redirect destination before following it. The implementation explicitly blocks private, loopback, link-local, multicast, reserved, and unspecified addresses.