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CVE-2026-102783MediumCVSS 6.3CVE published 8 October 2026Added to mySites.guru 8 October 2026

Gridbox (com_gridbox) 2.20.3.1 to 2.20.3.x - Language Installation CSRF and Image Preview Path Validation (fixed in 2.20.4.0)

Balbooa released Gridbox 2.20.4.0 on 8 October 2026 with two security fixes: a Cross-Site Request Forgery (CSRF) vulnerability in the language installation process, and improved file path validation in the image preview so images can only be read from inside the configured media directory. The CSRF flaw is in an administrator-only action, so it needs a logged-in Super User to be tricked into opening a crafted link or page; because that action installs software, the consequence is serious even though it cannot be triggered by an anonymous visitor alone. We confirmed both changes by comparing the public 2.20.4.0 package with earlier releases; both affected areas are present from 2.20.2 onwards. Reported by Sergiy Tryzhychynskyi, coordinated by the Joomla Security Strike Team. Not a mySites.guru finding. No CVE had been assigned at the time of writing; the severity shown is our own assessment, not an official CVSS score. Update to 2.20.4.0. Earlier versions are covered by separate rules with more serious advisories, and should also go straight to 2.20.4.0.

Is my site affected?

Affected
Gridbox from 2.20.3.1 up to but not including 2.20.4.0
Fixed in
2.20.4.0
What to do
Update Gridbox to 2.20.4.0 or later.
Check whether your sites are affected

How CVE-2026-102783 is scored

The base metrics as Joomla CNA published them, and what each one means for a site running an affected version. Threat and environmental metrics are left out: they describe a moment or a particular install rather than the flaw.

6.3 Medium

CVSS 4.0, scored by Joomla CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

How it is reached

AV:N Attack vector
Network. Reachable across the internet
AC:L Attack complexity
Low. Nothing to work around, it just works
AT:P Attack requirements
Present. Needs a particular deployment or race to line up
PR:N Privileges required
None. No account needed
UI:N User interaction
None. Nobody has to be tricked into anything

What it does to the site

VC:L Confidentiality
Low. Some data can be read
VI:N Integrity
None. Nothing can be altered
VA:N Availability
None. The site stays up

What it does beyond the site

SC:N Confidentiality
None. Other systems keep their data
SI:N Integrity
None. Other systems keep their integrity
SA:N Availability
None. Other systems stay up

The rule below is rated High for the set of 2 CVEs it covers together, not for this record on its own.

Timeline

  1. 8 October 2026CVE-2026-102783 record published by its CNA
  2. 8 October 2026mySites.guru check added for Gridbox (from 2.20.3.1 up to but not including 2.20.4.0)
  3. 8 October 2026We published: Gridbox 2.20.4.0 Fixes a Language Install CSRF and an Image Path Check

Rule details

Our disclosure post

Gridbox 2.20.4.0 Fixes a Language Install CSRF and an Image Path Check

Gridbox 2.20.4.0 Fixes a Language Install CSRF and an Image Path Check

Gridbox 2.20.4.0 fixes a CSRF flaw in language installation and tightens image preview path checks. Every Joomla site on 2.20.3.1 or older should update.

Other vulnerabilities in Gridbox

Updating for CVE-2026-102783 alone can leave a site on a release another rule still matches. These are the other flaws we check for in the same extension.

Gridbox

Latest safe version: 2.20.4.0

All 14 CVEs in Gridbox

References

CVE-2026-102783 questions

Which versions are affected by CVE-2026-102783?
CVE-2026-102783 affects Gridbox from 2.20.3.1 up to but not including 2.20.4.0. The fix is in 2.20.4.0.
How do I fix CVE-2026-102783?
Update Gridbox to 2.20.4.0 or later. Then confirm the installed version on the Joomla administrator's Extensions: Manage screen.
How severe is CVE-2026-102783?
Joomla CNA scores it 6.3 (Medium) under CVSS 4.0. In plain terms: reachable across the internet, no account needed and nobody has to be tricked into anything.

Running an affected version on a site you manage?

A free audit tells you which of your Joomla and WordPress sites run an affected version, which are out of date, and which have not been backed up. No card required. If a site is already compromised, fix.mysites.guru is a single fixed fee per incident, usually resolved the same day.

This check is part of the mySites.guru Joomla vulnerability scanner, which reads every installed extension's version on each audit. Browse the rest of the Joomla vulnerability database.

Rules current as of 8 October 2026.