CVE-2026-15981

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.

Affected Software

Weaknesses

• CWE-287: CWE-287 Improper Authentication

References

• https://www.wordfence.com/threat-intel/vulnerabilities/id/b412f60f-61ea-47b1-a3ef-17275f7951df?source=cve
• https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.4/class-mo-saml-login-validate.php#L118
• https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.4/class-mo-saml-utilities.php#L403
• https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.4/includes/lib/SAML2Core/class-mo-saml-xml-security-dsig.php#L938
• https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.4/includes/lib/SAML2Core/class-mo-saml-xml-security-key.php#L621
• https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.4/class-mo-saml-login-validate.php#L541
• https://plugins.trac.wordpress.org/changeset/3611421/miniorange-saml-20-single-sign-on

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