CVE-2026-58399

HIGHPre-NVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.0%, top 41% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
8.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.7Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

@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 v3
8.7
EG Score
8.7(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity87% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
59%
KEV
Not listed

Published

June 18, 2026

Last Modified

July 2, 2026

Advisory Details (2)

Auto-updated Jul 2, 2026
Patch available. Sources: github.
github Patch Available

Authentication bypass in @acastellon/auth v2.2.0 via spoofable headers in validateToken() (fixed in v2.3.0) · Advisory · antonio-castellon/module-auth · GitHub

Affected: v2.3.0) · Advisory · antonio-castellon/module-auth · GitHub

https://github.com/antonio-castellon/module-auth/security/advisories/GHSA-gfj5-979r-92pw
generic

SECURITY: Authentication bypass in @acastellon/auth v2.2.0 via spoofable headers in validateToken() (mTLS fix in 2.3.0+) · Issue #6 · antonio-castellon/module-auth · GitHub

https://github.com/antonio-castellon/module-auth/issues/6

Vendor Advisories for CVE-2026-58399(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@acastellon/auth—2.3.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 47× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 103 total refreshes for this CVE.

  1. 2026-08-30 01:22 UTCEPSS rescore
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  1. 2026-08-12 13:51 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-58399?
CVE-2026-58399 is a high vulnerability published on June 18, 2026. @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…
When was CVE-2026-58399 disclosed?
CVE-2026-58399 was first published in the National Vulnerability Database on June 18, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-58399 actively exploited?
CVE-2026-58399 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 40.9% of all scored CVEs.
What is the CVSS score of CVE-2026-58399?
CVE-2026-58399 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-58399?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-58399, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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