CVE-2026-15981
SAML Single Sign On <= 5.4.4 - Unauthenticated Authentication Bypass via SAMLResponse Parameter
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
- cyberlord92 · SAML Single Sign On – SSO Login
- CVSS v3.1 WORDFENCE
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 2.36% chance of exploitation in the next 30 days, 84th percentile
- Published
- 2026-07-23
- Updated
- 2026-07-24
Proof-of-concept exploits (2)
- Nxploited/CVE-2026-159810★ · 2026-07-26
- katranSefa/CVE-2026-159810★ · 2026-09-05