CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation
Date: 2026-06
Affected: nuget/CoreWCF.Primitives, nuget/CoreWCF.Primitives
Attack vector: deepfake
Category: vulnerability-disclosure
Severity: Critical
CVE: CVE-2026-54782
CWE: CWE-290
CWE-347
CVSS: 10 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N)

### Impact Full impersonation of any principal the trusted STS could have issued an assertion for — including administrative principals when the relying party grants them via SAML claims. Affects both SAML 1.1 and SAML 2.0. #### Preconditions Relying-party service is hosted with WSFederationHttpBinding or WS2007FederationHttpBinding (or any binding that triggers FederatedSecurityTokenManager for issued-token validation), and IdentityConfiguration is wired (UseIdentityConfiguration = true). Attacker can reach the service over the network and knows the trusted STS’s public certificate (public certs are by design discoverable). ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None


Mitigations:

Architectural layers (MAESTRO):