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CVE-2026-21623CriticalCVSS 9.4CVE published 16 January 2026Added to mySites.guru 16 January 2026

EasyDiscuss (com_easydiscuss) 4.0.2 to 5.0.15 - Authenticated Arbitrary File Upload, Stored XSS and Access Control Bypass

EasyDiscuss by StackIdeas, versions up to and including 5.0.15, is affected by four issues fixed together in 5.0.16: CVE-2026-21625, user-supplied uploads are validated by file extension only with no MIME type check, allowing dangerous file types to be stored; CVE-2026-21623 and CVE-2026-21624, missing input filtering leads to persistent XSS in forum post handling and in user avatar text handling; and CVE-2026-21626, access control settings for forum post custom fields are not applied to the JSON output type, disclosing restricted field data. All four require a registered forum account. Update to EasyDiscuss 5.0.16 or later. This rule starts at 4.0.2 to avoid matching the OSMap and Xmap EasyDiscuss companion plugins, which report their own low version numbers under the same element.

Is my site affected?

Affected
EasyDiscuss from 4.0.2 up to and including 5.0.15
Fixed in
Update to 5.0.16 or later
What to do
Update EasyDiscuss to 5.0.16 or later.
Check whether your sites are affected

How CVE-2026-21623 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.

9.4 Critical

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

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:N Attack requirements
None. Works against any affected install
PR:L Privileges required
Low. Any logged-in account will do
UI:P User interaction
Passive. Someone has to visit a page

What it does to the site

VC:H Confidentiality
High. Everything the site holds can be read
VI:H Integrity
High. Data and files can be altered at will
VA:H Availability
High. The site can be taken down

What it does beyond the site

SC:H Confidentiality
High. Data on other systems can be read
SI:H Integrity
High. Other systems can be altered
SA:H Availability
High. Other systems can be taken down

The rule below is rated High for the set of 4 CVEs it covers together, not for this record on its own.

Timeline

  1. 16 January 2026CVE-2026-21623 record published by its CNA
  2. 16 January 2026mySites.guru check added for EasyDiscuss (from 4.0.2 up to and including 5.0.15)

Rule details

Other vulnerabilities in EasyDiscuss

Updating for CVE-2026-21623 alone can leave a site on a release another rule still matches. These are the other flaws we check for in the same extension.

EasyDiscuss

Latest safe version: 5.0.16

References

CVE-2026-21623 questions

Which versions are affected by CVE-2026-21623?
CVE-2026-21623 affects EasyDiscuss from 4.0.2 up to and including 5.0.15.
How do I fix CVE-2026-21623?
Update EasyDiscuss to 5.0.16 or later. Then confirm the installed version on the Joomla administrator's Extensions: Manage screen.
How severe is CVE-2026-21623?
Joomla CNA scores it 9.4 (Critical) under CVSS 4.0. In plain terms: reachable across the internet, any logged-in account will do and someone has to visit a page.

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 5 October 2026.