Vulnerability Description
@acastellon/auth is an authentication control system for microservices. Versions prior to 2.3.0 appear to allow an unauthenticated authentication bypass in validateToken() through spoofable auth-user and Host request headers. The validateToken middleware contains a service-to-service bypass for auth-user: service-brother when req.get('host').startsWith(getHostName()). Both values involved in the check can be influenced by an unauthenticated HTTP client: auth-user is a request header, and Host is also client-controlled. As a result, a remote unauthenticated attacker can send a request with crafted headers and bypass token validation before the normal legacy/JWT/OIDC validation logic runs. A fix has been implemented in v2.3.0.
Related Weaknesses (CWE)
References
- https://github.com/antonio-castellon/module-auth/issues/6
- https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-9
- https://www.npmjs.com/package/@acastellon/auth/v/2.3.0
FAQ
What is CVE-2026-58399?
CVE-2026-58399 is a documented vulnerability. @acastellon/auth is an authentication control system for microservices. Versions prior to 2.3.0 appear to allow an unauthenticated authentication bypass in validateToken() through spoofable auth-user ...
How severe is CVE-2026-58399?
CVSS scoring is not yet available for CVE-2026-58399. Check NVD for updates.
Is there a patch for CVE-2026-58399?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.