Vulnerabilities / Defender Security / WPSEC-2026-0305
Defender Security <= 6.2.4 - Unauthenticated Firewall Lockout Bypass via 'wpmudev_is_staff' Cookie
Low 3.7
CWE-565Fixed in 6.3.0
- ID
- WPSEC-2026-0305
- Plugin
- Defender Security – Malware Scanner, Login Security & Firewall (defender-security)
- Affected
- from 3.3.0 before 6.3.0
- Remediation
- Update to 6.3.0 or later.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
- Weakness
- CWE-565
- Usage
- Plugin Low · Affected versions Low among sites WPSec scans, 2026-10-22
- Attack surface
- Defender Security on WPSec AttackSurface
- Fix released
- Published
Description
The Defender Security plugin for WordPress is vulnerable to a firewall protection bypass in versions 3.3.0 up to, and including, 6.2.4 due to the plugin accepting a client-supplied 'wpmudev_is_staff' cookie with the value '1' as proof of authenticated WPMU DEV staff access, without any signature or binding to a user. This makes it possible for unauthenticated attackers to skip the IP blocklist, active IP lockouts and user agent checks, and the two-factor authentication attempt limit. Exploitation requires the WPMU DEV Dashboard plugin to be connected with support staff remote access currently granted.
References
- https://wpsec.com/vuln/WPSEC-2026-0305/
- https://plugins.svn.wordpress.org/defender-security/tags/6.3.0/
- https://wordpress.org/plugins/defender-security/
Published by WPSec. Provided as is, without warranty. Corrections: contact us.
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