CVE-2026-54782: CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation
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.
Published Jun 19, 2026
Affected packages
CoreWCF.Primitives
- Ecosystem
- NuGet
- Affected
- < 1.8.1
- Fixed in
- 1.8.1
- Check
dotnet list package --include-transitive
CoreWCF.Primitives
- Ecosystem
- NuGet
- Affected
- >= 1.9.0, < 1.9.1
- Fixed in
- 1.9.1
- Check
dotnet list package --include-transitive
Advisory details
From the GitHub Advisory Database (CC BY 4.0).
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
References
How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology