Vulnerability · Published Jul 1, 2026 · Assigned by GitHub_M
CVE-2026-58399@acastellon/auth has an authentication bypass via spoofable headers in validateToken()
High 8.7
In plain English
A high-severity improper authentication in module-auth from antonio-castellon. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 62% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @acastellon/auth | 2.3.0 | GHSA-gfj5-979r-92pw |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| antonio-castellon | module-auth | < 2.3.0 |
Weakness: CWE-287 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-979r-92pw x_refsource_CONFIRM
- https://github.com/antonio-castellon/module-auth/issues/6 x_refsource_MISC
- https://www.npmjs.com/package/@acastellon/auth/v/2.3.0 x_refsource_MISC