Read the docs
TI-2026-42015 Aliases CVE-2026-58399GHSA-gfj5-979r-92pw

@acastellon/auth has an authentication bypass via spoofable headers in validateToken()

Priority MEDIUM 48CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.

Summary

@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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00973 62nd percentileScored 2026-11-07
Fix Fixed module-auth (antonio-castellon): 2.3.0@acastellon/auth (npm): 2.3.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
antonio-castellonmodule-authbefore 2.3.02.3.0Patch availableCNA
—@acastellon/auth (npm)before 2.3.02.3.0Patch availableGHSA-gfj5-979r-92pw
  • module-auth Vendorantonio-castellon Affected before 2.3.0 Fixed in 2.3.0 Patch available CNA
  • @acastellon/auth (npm) Vendor— Affected before 2.3.0 Fixed in 2.3.0 Patch available GHSA-gfj5-979r-92pw

Remediation

  • Fix · CNA module-auth (antonio-castellon) Fixed in 2.3.0
  • Fix · GHSA-gfj5-979r-92pw @acastellon/auth (npm) Fixed in 2.3.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-58399
  2. 2026-10-03 Alias added: GHSA-gfj5-979r-92pw

References

Other 4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences