CVE-2026-54781

highCVSS 7.4covered by 1 sourcefirst seen 2026-07-08

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.

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Exploitation outlook

Low exploitation risk0.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all EPSS-scored CVEs.

Advisory coverage (1)

highCVE-2026-54781: CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. …nvd · 2026-07-08

External references

NVD record for CVE-2026-54781

CVE.org record

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