SAML Single Sign On <= 5.4.4 - Unauthenticated Authentication Bypass via SAMLResponse Parameter

Summary

The SAML Single Sign On – SSO Login plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 5.4.4. This is due to the mo_saml_validate_signature() function performing a loose boolean check on the raw tri-state integer returned by PHP's openssl_verify(), causing an error return value of -1 to be evaluated as truthy and therefore treated as a successful signature verification. This makes it possible for unauthenticated attackers to log in as any existing WordPress user, including administrators, by submitting a crafted SAMLResponse containing an attacker-controlled NameID and a deliberately malformed signature value that triggers an OpenSSL processing error — bypassing verification entirely and resulting in wp_set_auth_cookie() being called for the targeted account.

Timeline

1. Jul 23, 2026, 8:33 PM UTCCVE published
2. Jul 24, 2026, 10:05 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: total

3. Jul 24, 2026, 10:06 PM UTCRecord last updated

Affected versions

• cyberlord92 SAML Single Sign On – SSO Login

  through 5.4.4

References 9