GHSA-mfvp-7p3v-x9mh Casdoor SAML callback handler accepts any well-formed SAMLResponse sent to /api/acs without verifying that it corresponds to an AuthnRequest

• Go github.com/casdoor/casdoor: <= 1.1000.1-0.20260321120606-239e8bd69487 (no fix yet)

In Casdoor versions 2.362.0 and earlier, the SAML callback handler in controllers/auth.go accepts any well-formed SAMLResponse sent to /api/acs without verifying that it corresponds to an AuthnRequest previously issued by Casdoor. Additionally, if an administrator disables or deletes an IdP (Identity Provider) after a SAML flow has started, the handler still processes the response using the provider snapshot loaded at the start of the request. As a result, an attacker controlling a registered upstream IdP can send unsolicited SAML responses, or replay a legitimately captured response in a different session or after the original flow has ended. In both cases, Casdoor accepts the response and issues a session, enabling persistent unauthorized access.