← Vulnerability feed

Vulnerability record · CVE-2026-58399 · published 1 July 2026

CVE-2026-58399: Improper authentication 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 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.

8.7 CVSS 4.0 High EPSS 0.97% · top 39.5% CWE-287 · Improper authentication Deferred
8.7CVSS 4.0 base score
0.97%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
2 Jul 2026Last modified by NVD

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.

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/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:

References

LinkTags
https://github.com/antonio-castellon/module-auth/issues/6
https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-979r-92pw
https://www.npmjs.com/package/@acastellon/auth/v/2.3.0

Track CVE-2026-58399 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.5CVE-2026-42018JFrog Artifactory improper authentication leaks anonymous tokenJFrog Artifactory can return an internal anonymous-user token to an unauthenticated caller even when anonymous access is disabled. Because the token …KEVEPSS 9.8%analysed9.8CVE-2026-82329JFrog Artifactory improper authentication allows admin takeoverJFrog Artifactory contains an improper authentication weakness (CWE-287) that, under default configuration, may let an unauthenticated attacker with …KEVEPSS 14%analysed8.8CVE-2026-59822LiteLLM MCP endpoint auth bypass via OAuth2 passthrough fallbackLiteLLM's MCP Streamable HTTP endpoint, prior to 1.84.0, let an unauthenticated attacker send a fabricated Authorization header that triggered an OAu…KEVEPSS 0.84%analysed10.0CVE-2026-49869Kestra OSS auth bypass via path suffix match enables RCEKestra OSS AuthenticationFilter whitelists the public config endpoint using request.getPath().endsWith("/configs"), a suffix match instead of an exac…KEVEPSS 2.1%analysed9.8CVE-2023-49105ownCloud Server WebDAV authentication bypass via pre-signed URLsownCloud core before 10.13.1 accepts pre-signed URLs even when the file owner has no signing-key configured, so the signature check is effectively sk…KEVEPSS 43%analysed9.8CVE-2026-65400Apple macOS Screen Sharing authentication bypassAn improper authentication flaw in Apple macOS Screen Sharing allows a network attacker to authenticate without valid credentials. Apple fixed it via…KEVEPSS 1.2%analysed9.3CVE-2026-16232Check Point SmartConsole authentication bypass grants admin tokenCheck Point SmartConsole login contains an improper authentication flaw (CWE-287) that lets an unauthenticated remote attacker obtain an application …KEVEPSS 78%analysed9.8CVE-2026-46817Oracle E-Business Suite Payments missing authentication allows takeoverOracle Payments in Oracle E-Business Suite 12.2.3 through 12.2.15 contains an easily exploitable flaw in the File Transmission component. An unauthen…KEVEPSS 0.81%analysed

Source: NIST National Vulnerability Database (record CVE-2026-58399), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.