IdentityModel Extensions for .NET provide assemblies for web developers that wish to use federated identity providers for establishing the caller's identity. Anyone leveraging the `SignedHttpRequest`protocol or the `SignedHttpRequestValidator`is vulnerable. Microsoft.IdentityModel trusts the `jku`claim by default for the `SignedHttpRequest`protocol. This raises the possibility to make any remote or local `HTTP GET` request. The vulnerability has been fixed in Microsoft.IdentityModel.Protocols.SignedHttpRequest. Users should update all their Microsoft.IdentityModel versions to 7.1.2 (for 7x) or higher, 6.34.0 (for 6x) or higher.

An issue was discovered in IdentityModel (aka ScottBrady.IdentityModel) before 1.3.0. The Branca implementation allows an attacker to modify and forge authentication tokens.

An authentication bypass vulnerability exists in Windows Communication Foundation (WCF) and Windows Identity Foundation (WIF), allowing signing of SAML tokens with arbitrary symmetric keys, aka 'WCF/WIF SAML Token Authentication Bypass Vulnerability'.