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Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

CVE-2026-54774CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate

High 7.4

In plain English

A high-severity insufficient verification of data authenticity in CoreWCF from CoreWCF. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.4High
Exploit odds (30 days)0.2%top 89.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
NuGetcorewcf.primitives1.8.1GHSA-rpj7-hr7h-w6p9
NuGetcorewcf.primitives1.9.1GHSA-rpj7-hr7h-w6p9

Affected products (as reported)

VendorProductVersions
CoreWCF CoreWCF >= 1.9.0, < 1.9.1< 1.8.1

Weakness: CWE-345, CWE-347 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References