CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
Date: 2026-06
Affected: nuget/CoreWCF.Primitives, nuget/CoreWCF.Primitives
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-54774
CWE: CWE-345
CWE-347
CVSS: 7.4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N)

### Impact When a service is configured to validate SAML tokens using a method other than X.509 certificate signing, the final signature verification is skipped. #### Preconditions The service is configured to authenticate using SAML tokens and an out of band token resolver (commonly the IssuerTokenResolver of IssuedTokenServiceCredential) holds a non-X.509 SecurityToken whose key identifier the attacker can reference in the assertion’s `<KeyInfo>` - for example a `BinarySecretSecurityToken` representing the symmetric proof key issued by a WS-Trust symmetric-key holder-of-key STS. ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None


Mitigations:

Architectural layers (MAESTRO):