What is CVE-2026-66490?

CVE-2026-66490 is a medium-severity vulnerability in Balbooa Gridbox, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-29.

How severe is CVE-2026-66490?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Balbooa Gridbox

CVE-2026-66490

Joomla Extension - balbooa.com - Stored cross-site scripting via a comment avatar in Gridbox < 2.20.2

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-07-29 · last modified 2026-10-23.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (18.4th percentile), scored 2026-10-28.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Balbooa Gridbox
Balbooa.com Gridbox Extension For Joomla — versions 1.0.0-2.20.1

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.balbooa.com/gridbox (Product, product)
mysites.guru/blog/gridbox-23-critical-vulnerabilities/ (Third Party Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2026-66490?: CVE-2026-66490 is a medium-severity vulnerability in Balbooa Gridbox, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-29.
How severe is CVE-2026-66490?: Medium severity. CVSS v3 base score is 6.1 out of 10.