CVE-2026-41896: Coolify: Unauthenticated Deployment Trigger via Webhook HMAC Bypass with Null Secret
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 manualwebhooksecretgithub 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 hashhmac() function silently coerces a null key to an empty string ''. So when the secret is null, the server computes hashhmac('sha256', $payload, '') — a deterministic value that any attacker can calculate independently. By sending X-Hub-Signature-256: sha256=<hashhmac('sha256', payload, '')>, an unauthenticated attacker can forge a valid signature and trigger deployments. This vulnerability is fixed in 4.0.0-beta.474.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Coolifyto a version that resolves this vulnerability.Fixed in 4.0.0-beta.474
Event History
Frequently Asked Questions
What is the severity of CVE-2026-41896?
CVE-2026-41896 has a high severity rating of 7.5.
How do I fix CVE-2026-41896?
To fix CVE-2026-41896, upgrade to Coolify version 4.0.0-beta.474 or later where the HMAC key handling has been addressed.
What type of vulnerability is CVE-2026-41896?
CVE-2026-41896 is an unauthenticated deployment trigger vulnerability via webhook HMAC bypass.
What impact does CVE-2026-41896 have on Coolify users?
CVE-2026-41896 may allow unauthorized users to trigger deployments on Coolify, resulting in potential unauthorized changes to applications.
Who is affected by CVE-2026-41896?
Users of Coolify prior to version 4.0.0-beta.474 are affected by CVE-2026-41896.