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Back to active CVEs
Medium · CVSS 6.5CVE-2026-81868GHSA-5MQ7-RWHJ-4FH9

Steeltoe: Header-forwarded client cert lacks proof of private-key possessionCVE-2026-81868

Answer in brief

CVE-2026-81868 records a Medium severity (CVSS 6.5) vulnerability in Steeltoe: Header-forwarded client cert lacks proof of private-key possession. The current sources do not mark it as known exploited. The current feed maps SteeltoeOSS/security-advisories (generic), Steeltoe.Security.Authorization.Certificate (nuget). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 30, 2026Source checked Nov 1, 2026First seen by HOL Sep 17, 2026Material review Sep 30, 2026
Upstream Advisory

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-288, CWE-295
Source
CVE List V5
Source checked
Nov 1, 2026
References
5 linked sources
Open source record

Key facts

Risk
Medium · CVSS 6.5
Exploitation
Not marked as known exploited
Affected software
2 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps SteeltoeOSS/security-advisories (generic), Steeltoe.Security.Authorization.Certificate (nuget). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
SteeltoeOSS/security-advisoriesgeneric<4.3.04.3.0
Steeltoe.Security.Authorization.Certificatenuget<=4.2.04.3.0

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for SteeltoeOSS/security-advisories, Steeltoe.Security.Authorization.Certificate.
  2. 2Review the reported fix. Update SteeltoeOSS/security-advisories to 4.3.0; Steeltoe.Security.Authorization.Certificate to 4.3.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Sep 17, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Sep 30, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Sep 17, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • NVD vulnerability recordnvd.nist.gov
Upstream source description

Steeltoe is an open source project that provides a collection of libraries that helps users build cloud-native applications. Prior to 4.3.0, Steeltoe.Security.Authorization.Certificate deployments using AddOrgAndSpacePolicies() and UseCertificateAuthorization() trust the public certificate supplied in the X-Client-Cert request header without proving possession of the corresponding private key. Common Cloud Foundry routers do not remove this header from inbound requests. When inbound requests are not restricted to a known trusted proxy source IP, an attacker who obtains the public certificate of an application instance in the target organization or space and can reach the application can spoof X-Client-Cert to bypass the SameOrg and SameSpace policies for the certificate validity period. This issue is fixed in version 4.3.0.

Quoted source text, attributed separately from HOL analysis.