CVE-2026-41896

Description

Coolify is an open-source and self-hostable tool for managing servers, applications, and databases. Prior to 4.0.0-beta.474, the HMAC key is the application-s manual_webhook_secret_github field, which is used by Coolify-s webhook endpoints to validate incoming requests, is nullable with no default — meaning newly created applications have a null webhook secret. PHP-s hash_hmac() function silently coerces a null key to an empty string --. So when the secret is null, the server computes hash_hmac(-sha256-, $payload, --) — a deterministic value that any attacker can calculate independently. By sending X-Hub-Signature-256: sha256=<hash_hmac(-sha256-, payload, --)>, an unauthenticated attacker can forge a valid signature and trigger deployments. This vulnerability is fixed in 4.0.0-beta.474.