CVE-2026-15013: cyberlord92 saml single sign on – sso login

Vulnerability summary

CVE-2026-15013 is a critical (CVSS 9.8) vulnerability in cyberlord92 saml single sign on – sso login. EPSS estimates a 1.50% chance of exploitation in the next 30 days, higher than 74.1% of scored vulnerabilities. 1 public exploit is recorded. Fixed in 5.4.4.

Timeline

1. 16-07-2026
   PublishedVulnerability first disclosed.
2. 07-08-2026
   Last modifiedVulnerability information updated.

Description

The SAML Single Sign On – SSO Login plugin for WordPress is vulnerable to Authentication Bypass via SAML Signature Algorithm Confusion in all versions up to, and including, 5.4.3. The vulnerability exists because `Mo_SAML_Utilities::mo_saml_cast_key()` reads the `SignatureMethod` Algorithm attribute directly from the attacker-controlled `SAMLResponse` parameter rather than enforcing the locally configured algorithm, causing the plugin to recast the IdP's RSA public key as an HMAC-SHA1 shared secret and validate the forged signature against it. This makes it possible for unauthenticated attackers to forge a SAML assertion targeting any WordPress account — including administrators — obtain valid WordPress authentication cookies, and achieve full administrator-level account takeover.

• CWE-347Improper Verification of Cryptographic SignatureThe product does not verify, or incorrectly verifies, the cryptographic signature for data.