CVE-2026-58399
@acastellon/auth has an authentication bypass via spoofable headers in validateToken()
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.
INFO
Published Date :
July 1, 2026, 3:17 p.m.
Last Modified :
Oct. 25, 2026, 5:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update @acastellon/auth to version 2.3.0 or later.
- Review and test authentication logic.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-58399.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-58399 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-58399
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-58399 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-58399 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 25, 2026
Action Type Old Value New Value Added Translation Title: module-auth de antonio-castellon, Description: @acastellon/auth es un sistema de control de autenticación para microservicios. Las versiones anteriores a la 2.3.0 parecen permitir una omisión de autenticación no autenticada en validateToken() a través de encabezados de solicitud auth-user y Host falsificables. El middleware validateToken contiene una omisión de servicio a servicio para auth-user: service-brother cuando req.get(’host’).startsWith(getHostName()). Ambos valores involucrados en la verificación pueden ser influenciados por un cliente HTTP no autenticado: auth-user es un encabezado de solicitud, y Host también es controlado por el cliente. Como resultado, un atacante remoto no autenticado puede enviar una solicitud con encabezados manipulados y omitir la validación del token antes de que se ejecute la lógica de validación normal de legacy/JWT/OIDC. Se ha implementado una solución en la v2.3.0. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 02, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-58399', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-02T14:25:47.187429Z'} -
New CVE Received by [email protected]
Jul. 01, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'antonio-castellon', 'product': 'module-auth', 'versions': [{'status': 'affected', 'version': '< 2.3.0'}]}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-287 Added Reference https://github.com/antonio-castellon/module-auth/issues/6 Added Reference https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-979r-92pw Added Reference https://www.npmjs.com/package/@acastellon/auth/v/2.3.0