# CVE-2026-66490: Balbooa Gridbox stored XSS in comment avatar

Source: https://junglewise.ai/threats/cve-2026-66490-balbooa-gridbox-stored-xss-in-comment-avatar  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-29. Updated: 2026-07-29  
License: CC BY 4.0 with a link back

CVE-2026-66490 · Severity: info · CVSS 6.1 · Published 2026-07-29

Gridbox, a popular page-building tool for Joomla websites, contains a security flaw in its comment system. An attacker can use this flaw to inject malicious scripts into the avatar section of a comment, which will then run in the browser of anyone viewing that page. This could allow unauthorized individuals to steal session information or perform actions on behalf of other users, including site administrators.

Technologies: [Balbooa Gridbox](https://junglewise.ai/threats/technologies/gridbox). Vendors: [Balbooa](https://junglewise.ai/threats/vendors/balbooa).

## Quick answers

**Is CVE-2026-66490 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66490 being exploited in the wild.

**How severe is CVE-2026-66490?** Informational severity, with a CVSS score of 6.1, published 29 July 2026.

**Which products and versions are affected?** Balbooa Gridbox 1.0.0-2.20.1.

**Is there a fix for CVE-2026-66490?** A patch was published on 2026-07-20: Initial fixes attempted in version 2.20.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-66490 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-66490?** Check whether you run Balbooa Gridbox at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stored cross-site scripting (XSS) vulnerability exists in the Balbooa Gridbox extension for Joomla (com_gridbox) in versions prior to 2.20.2. The vulnerability is located in the comment avatar component, where user-supplied input is not properly neutralized before being rendered on the page (CWE-79). An unauthenticated or low-privileged attacker can upload or reference a malicious payload within a comment avatar. When other users, including administrators, view the affected page, the script executes in their browser context. This can lead to session hijacking, unauthorized administrative actions, or further exploitation of the site. The issue is resolved in version 2.20.2.

## Affected products

- balbooa.com Gridbox extension for Joomla 1.0.0-2.20.1

## Timeline

- 2026-07-20: patched: Initial fixes attempted in version 2.20.1
- 2026-07-29: disclosed: Full audit results and CVE assigned
- 2026-07-29: advisory: Final fix released in version 2.20.2

## References

- [https://mysites.guru/blog/gridbox-23-critical-vulnerabilities/](https://mysites.guru/blog/gridbox-23-critical-vulnerabilities/)
- [https://www.balbooa.com/gridbox](https://www.balbooa.com/gridbox)

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