# Defender Security <= 6.4.0 - Unauthenticated Two-Factor Authentication Bypass via Brute Force

- **ID:** WPSEC-2026-2785
- **Plugin:** Defender Security – Malware Scanner, Login Security & Firewall (`defender-security`), https://wordpress.org/plugins/defender-security/
- **Affected versions:** all versions before 6.4.1
- **Fixed in:** 6.4.1 (Update to 6.4.1 or later.)
- **Severity:** High 7.4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N)
- **Weakness:** CWE-307
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-11-10)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/defender-security
- **Fix released:** 2026-11-09
- **Published:** 2026-11-10
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2785/

## Description

The Defender Security plugin for WordPress is vulnerable to Two-Factor Authentication Bypass via brute force in all versions up to, and including, 6.4.0, due to failed two-factor code attempts only being counted and locked out when the Login Protection feature (disabled by default) was enabled. This makes it possible for unauthenticated attackers who already know a user's password to guess the two-factor code without limit and log in as that user.

## References

- https://wpsec.com/vuln/WPSEC-2026-2785/
- https://plugins.svn.wordpress.org/defender-security/tags/6.4.1/
- https://wordpress.org/plugins/defender-security/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2785/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.