Admidio is an open-source user management solution. Prior to version 5.0.9, the Admidio SAML Identity Provider implementation discards the return value of its validateSignature() method at both call sites (handleSSORequest() line 418 and handleSLORequest() line 613). The method returns error strings on failure rather than throwing exceptions, but the developer believed it would throw (per comments on lines 416 and 611). This means the smc_require_auth_signed configuration option is completely ineffective — unsigned or invalidly-signed SAML AuthnRequests and LogoutRequests are processed identically to properly signed ones. This issue has been patched in version 5.0.9.

Admidio Ignores SAML Signature Validation Result, Processes Forged AuthnRequests and LogoutRequests