CVE-2026-81868

Steeltoe: Header-forwarded client cert lacks proof of private-key possession

Published Sep 17, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-5mq7-rwhj-4fh9 Steeltoe: Header-forwarded client cert lacks proof of private-key possession
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Steeltoeoss
Steeltoeoss security-advisories
Vendors & Products Steeltoeoss
Steeltoeoss security-advisories
Type Values Removed Values Added
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.
Title Steeltoe: Header-forwarded client cert lacks proof of private-key possession
Weaknesses CWE-288
CWE-295
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 23, 2026, 6:46 PM
Reserved
Aug 27, 2026, 5:48 PM
Status
Awaiting Analysis
Published
Sep 17, 2026, 4:17 PM
Modified
Sep 30, 2026, 5:31 PM