Executive brief
Gridbox, a popular drag-and-drop page builder for the Joomla content management system, contains a critical security flaw that allows unauthorized individuals to gain full administrative control. By simply setting a specific browser cookie, an attacker can bypass the login process and access the site as a 'Super User' without needing a password. This level of access allows an attacker to modify the website, steal data, or potentially take over the entire web server.
Technical details
A critical authentication bypass exists in the Balbooa Gridbox extension for Joomla due to improper validation of user-supplied identity markers. The extension trusts a value provided in a browser cookie as proof of identity without verifying it against a valid session or password. An unauthenticated attacker can exploit this by setting a cookie to a known administrator's username, granting them immediate Super User privileges. Because Joomla Super Users can edit PHP template files through the administrative interface, this vulnerability effectively provides a path to Remote Code Execution (RCE). The issue is fixed in version 2.20.1.
Affected products
- Balbooa Gridbox extension for Joomla 1.0.0-2.20.0.2
Timeline
- 2025-10-21: other: Vulnerable version 2.20.0.2 released
- 2026-07-17: other: Vulnerability discovered and reported to vendor by mySites.guru
- 2026-07-20: patched: Fixed version 2.20.1 released
- 2026-07-20: disclosed: Public disclosure by mySites.guru and CVE assignment