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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| WordPress plugin | SAML Single Sign On – SSO Login | <= 5.4.3 | 5.4.4 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-347- Platform
- WordPress
- Package
SAML Single Sign On – SSO Login- Disclosed
- 15.07.2026
- Updated
- 11.10.2026 10:23
Sources and licenses
Wordfence Intelligence - ee95092d-6351-4612-872d-284165bc1201 - Wordfence Intelligence
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Copyright 2012-2026 Defiant Inc.
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Vulnerability history: SAML Single Sign On – SSO Login
All published vulnerabilities of this package (WordPress plugin), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 11
- First → latest
- 05.2019 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 3
- High 4
- Medium 4
Disclosures per year
- 2019: 2
- 2020: 1
- 2021: 0
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 6
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SAML Single Sign On <= 5.4.3 - Unauthenticated Authentication Bypass via 'SAMLResponse' Parameter Signature Algorithm Confusion this entry
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