Medium · published August 11, 2026
A server-side request forgery vulnerability in Apioo Fusio 8.8.3 allows authenticated consumer-role users to make the server issue HTTP requests to internal network addresses by registering a webhook URL pointing to an internal host. The webhook registration endpoint validates URL syntax via FILTER_VALIDATE_URL but applies no IP or host denylist. When the registered event fires, the server issues an HTTP POST to the attacker-supplied internal URL.