Is CVE-2026-54774 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-54774?

CVE-2026-54774 has a CVSS v3 severity of HIGH (7.4).

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CVE-2026-54774

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, SamlSerializer skips final SignatureValue verification when a CoreWCF service validates SAML tokens using a non-X.509 signing token, allowing an attacker to reference a non-X.509 SecurityToken key identifier and bypass assertion signature verification. This issue is fixed in versions 1.8.1 and 1.9.1.