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.
History

Mon, 27 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
First Time appeared Cyberlord92
Cyberlord92 oauth Single Sign On – Sso (oauth Client)
Wordpress
Wordpress wordpress
Vendors & Products Cyberlord92
Cyberlord92 oauth Single Sign On – Sso (oauth Client)
Wordpress
Wordpress wordpress

Fri, 24 Jul 2026 22:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 23 Jul 2026 21:45:00 +0000

Type Values Removed Values Added
Description 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.
Title SAML Single Sign On <= 5.4.4 - Unauthenticated Authentication Bypass via SAMLResponse Parameter
Weaknesses CWE-287
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Wordfence

Published: 2026-07-23T20:33:51.362Z

Updated: 2026-07-24T22:06:10.389Z

Reserved: 2026-07-16T16:55:30.527Z

Link: CVE-2026-15981

cve-icon Vulnrichment

Updated: 2026-07-24T22:06:03.900Z

cve-icon NVD

No data.

cve-icon Redhat

No data.