Authentication Bypass by Alternate Name
Sustainsys.Saml2 library adds SAML2P support to ASP.NET websites, allowing the website to act as a SAML2 Service Provider. In versions through 1.0.2, and 2.0.0 through 2.9.1, when a response is processed, the issuer of the Identity Provider is not sufficiently validated. This could allow a malicious identity provider to craft a Saml2 response that is processed as if issued by another identity provider. It is also possible for a malicious end user to cause stored state intended for one identity provider to be used when processing the response from another provider. An application is impacted if they rely on any of these features in their authentication/authorization logic: the issuer of the generated identity and claims; or items in the stored request state (AuthenticationProperties). The `AcsCommandResultCreated` notification can be used to add the validation required if an upgrade to patched packages is not possible.
CWE-289 - Authentication Bypass by Alternate Name
The software performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.