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Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

CVE-2026-54782CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation

Critical 10.0

In plain English

A critical-severity authentication bypass by spoofing 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 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)10.0Critical
Exploit odds (30 days)0.4%top 64.1% 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, CoreWCF SAML 1.1 and SAML 2.0 token validation does not correctly resolve the issuer signing key or require signed tokens when IdentityConfiguration is used with federated bindings, allowing an unauthenticated remote attacker to impersonate any principal the trusted STS could issue. This issue is fixed in versions 1.8.1 and 1.9.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
NuGetcorewcf.primitives1.8.1GHSA-xjr9-gg9q-jx3v
NuGetcorewcf.primitives1.9.1GHSA-xjr9-gg9q-jx3v

Affected products (as reported)

VendorProductVersions
CoreWCF CoreWCF >= 1.9.0, < 1.9.1< 1.8.1

Weakness: CWE-290, CWE-347 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

References