---
id: CVE-2026-15013
title: >-
  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
summary: >-
  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_s…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-347
published: '2026-07-16'
updated: '2026-08-07'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-15013'
references:
  - url: >-
      https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.3/class-mo-saml-login-validate.php#L119
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.3/class-mo-saml-utilities.php#L416
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.3/class-mo-saml-utilities.php#L444
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.3/class-mo-saml-utilities.php#L561
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.3/includes/lib/SAML2Core/class-mo-saml-xml-security-key.php#L722
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/changeset?reponame=&old=3601345%40miniorange-saml-20-single-sign-on&new=3601345%40miniorange-saml-20-single-sign-on
    label: security@wordfence.com
  - url: >-
      https://www.wordfence.com/threat-intel/vulnerabilities/id/ee95092d-6351-4612-872d-284165bc1201?source=cve
    label: security@wordfence.com
  - url: 'http://seclists.org/fulldisclosure/2026/Aug/33'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - exploit-available
epss: 0.01504
epssPercentile: 0.73211
ingestedAt: '2026-08-07T22:17:38.060Z'
exploitAvailable: true
exploits:
  exploitdb: true
  github: 1
  githubRepos:
    - 'https://github.com/zer0dayf/CVE-2026-15013'
  checkedAt: '2026-09-25T08:20:50.444Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.