CVE-2026-54781

CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced

Published Jul 8, 2026 CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed
Description
CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, CoreWCF SAML token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom confirmation method assertions to authenticate a subject without proving authority over the assertion. This issue is fixed in versions 1.8.1 and 1.9.1.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-48pq-2xq3-c2m4 CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced
History
Type Values Removed Values Added
Metrics ssvc

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

Type Values Removed Values Added
First Time appeared Corewcf
Corewcf corewcf
Vendors & Products Corewcf
Corewcf corewcf
Type Values Removed Values Added
Description CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, CoreWCF SAML token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom confirmation method assertions to authenticate a subject without proving authority over the assertion. This issue is fixed in versions 1.8.1 and 1.9.1.
Title CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced
Weaknesses CWE-287
CWE-345
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 9, 2026, 2:40 PM
Reserved
Jun 15, 2026, 11:23 PM
Status
Deferred
Published
Jul 8, 2026, 11:16 PM
Modified
Jul 9, 2026, 4:29 PM