EUVD-2026-308997

fkie_cve-2026-41669

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.

GHSA-25cw-98hg-g3cg — Admidio Ignores SAML Signature Validation Result, Processes Forged AuthnRequests and LogoutRequests

Affected: Packagist: admidio/admidio

## Summary

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.

## Details

The `validateSignature()` method at `src/SSO/Service/SAMLService.php:355` has three possible return paths:

```php // Line 355-392 public function validateSignature(SAMLClient $client, SamlMessage $message, bool $required = false): bool|string { global $gL10n; $certPem = $client->getValue('smc_x509_certificate'); if (!$certPem) { if ($required) { return $gL10n->get('SYS_SSO_SAML_SIGNATURE_KEY_MISSING'); // Returns STRING, not throw } else { return false; } } // ... $signatureReader = $message->getSignature(); if (is_null($signatureReader)) { if ($required) { return $gL10n->get('SYS_SSO_SAML_SIGNATURE_MISSING'); // Returns STRING, not throw } else { return false; } } try { $ok = $signatureReader->validate($key); if ($ok) { return true;…

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EUVD-2026-308997

fkie_cve-2026-41669

GHSA-25cw-98hg-g3cg — Admidio Ignores SAML Signature Validation Result, Processes Forged AuthnRequests and LogoutRequests