Vulnerability-Lookup

CVE-2026-58399 (GCVE-0-2026-58399)

Vulnerability from cvelistv5 – Published: 2026-07-01 14:25 – Updated: 2026-07-02 14:26

Title

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

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.

Severity

8.7 (High)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-02 14:25 UTC

CWE

CWE-287 - Improper Authentication

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/antonio-castellon/module-auth/…	x_refsource_CONFIRM
https://github.com/antonio-castellon/module-auth/…	x_refsource_MISC
https://www.npmjs.com/package/@acastellon/auth/v/2.3.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
antonio-castellon	module-auth	Affected: < 2.3.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-58399

Vulnerability from fkie_nvd - Published: 2026-07-01 15:17 - Updated: 2026-07-02 17:54

Severity

8.7 (High) - 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

Summary

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "module-auth",
          "vendor": "antonio-castellon",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.3.0"
            }
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        }
      ],
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    }
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    }
  ],
  "id": "CVE-2026-58399",
  "lastModified": "2026-07-02T17:54:15.243",
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          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
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GHSA-GFJ5-979R-92PW

Vulnerability from github – Published: 2026-06-18 17:22 – Updated: 2026-07-01 14:30

Summary

@acastellon/auth: Authentication bypass via spoofable headers in validateToken()

Details

@acastellon/auth v2.2.0 appears 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.

Impact: An attacker may be able to access routes protected by validateToken() without a valid token. In deployments where downstream services trust auth-user or is-* headers, this may also lead to privilege escalation.

Affected package: @acastellon/auth v2.2.0

Affected code: auth.js, validateToken() The issue is related to the service-brother bypass and getHostName() check.

Example request:

GET /protected HTTP/1.1
Host: <configured CNAME or hostname>
auth-user: service-brother
is-admin: true

Expected behavior: The request should require a valid authentication token.

Actual behavior: The middleware calls next() before token validation.

Fix implemented in v2.3.0+:

Removed the spoofable bypass. Always sanitize incoming auth-user and is-* headers. Added mTLS client certificate based service auth (with optional TRUSTED_MTLS_SERVICES allowlist). Updated consumers (rest, graphql, dns-client) for mTLS support. Unit tests added for sanitization + mTLS path.

Severity

9.3 (Critical)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@acastellon/auth"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-58399"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-290"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T17:22:47Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "@acastellon/auth v2.2.0 appears to allow an unauthenticated authentication bypass in validateToken() through spoofable auth-user and Host request headers.\n\nThe validateToken middleware contains a service-to-service bypass for auth-user: service-brother when req.get(\u0027host\u0027).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.\n\nImpact:\nAn attacker may be able to access routes protected by validateToken() without a valid token. In deployments where downstream services trust auth-user or is-* headers, this may also lead to privilege escalation.\n\nAffected package:\n@acastellon/auth v2.2.0\n\nAffected code:\nauth.js, validateToken()\nThe issue is related to the service-brother bypass and getHostName() check.\n\nExample request:\n```\nGET /protected HTTP/1.1\nHost: \u003cconfigured CNAME or hostname\u003e\nauth-user: service-brother\nis-admin: true\n```\n\nExpected behavior:\nThe request should require a valid authentication token.\n\nActual behavior:\nThe middleware calls next() before token validation.\n\nFix implemented in v2.3.0+:\n\nRemoved the spoofable bypass.\nAlways sanitize incoming auth-user and is-* headers.\nAdded mTLS client certificate based service auth (with optional TRUSTED_MTLS_SERVICES allowlist).\nUpdated consumers (rest, graphql, dns-client) for mTLS support.\nUnit tests added for sanitization + mTLS path.",
  "id": "GHSA-gfj5-979r-92pw",
  "modified": "2026-07-01T14:30:32Z",
  "published": "2026-06-18T17:22:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-979r-92pw"
    },
    {
      "type": "WEB",
      "url": "https://github.com/antonio-castellon/module-auth/issues/6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/antonio-castellon/module-auth"
    },
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/package/@acastellon/auth/v/2.3.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "@acastellon/auth: Authentication bypass via spoofable headers in validateToken()"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-58399 (GCVE-0-2026-58399)

FKIE_CVE-2026-58399

GHSA-GFJ5-979R-92PW

Tags

Sightings

Nomenclature

Related by attack behaviour