CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation
Description
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
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
CoreWCF.PrimitivesNuGet | < 1.8.1 | 1.8.1 |
CoreWCF.PrimitivesNuGet | >= 1.9.0, < 1.9.1 | 1.9.1 |
Affected products
1Patches
Vulnerability mechanics
References
2News mentions
1- CoreWCF: 13 CVEs Disclosed in a Single Day — Critical SAML Bypass and WS-Security FlawsVypr Intelligence · Jun 19, 2026