CVE-2026-15013

SAML Single Sign On <= 5.4.3 - Unauthenticated Authentication Bypass via 'SAMLResponse' Parameter Signature Algorithm Confusion

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.

Affected

cyberlord92 · SAML Single Sign On – SSO Login

CVSS v3.1 WORDFENCE

9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

1.50% chance of exploitation in the next 30 days, 74th percentile

Published

2026-07-16

Updated

2026-08-07

Proof-of-concept exploits (1)

• zer0dayf/CVE-2026-150131★ · 2026-07-27

ExploitDB entries (1)

• https://www.exploit-db.com/exploits/52668

References

• CVE Record
• NVD entry

Related

• CVE-2026-65008
• CVE-2026-87902