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CVE-2026-61900CriticalCVSS 10.0CVE published 20 July 2026Added to mySites.guru 17 July 2026

jDownloads (com_jdownloads) 4.1.0 to 4.1.5 - Unauthenticated Arbitrary File Upload (malware hosting, RCE on misconfigured hosts)

jDownloads 4.1.0 to 4.1.5 ship a standalone, unauthenticated file-upload handler at administrator/components/com_jdownloads/assets/upload/upload-handler.php. The handler was introduced in the 4.1.0 release and is absent from 4.0.52 and earlier. The vendor confirms it was a test/experimental upload component unintentionally included in the release package. The endpoint has no _JEXEC guard, no Joomla session, no CSRF token and no permission check, and it bypasses jDownloads' own upload blacklist - it enforces only its own hardcoded extension allow-list (zip, rar, 7z, tar, gz, pdf, exe, msi, dat, mp3, mp4, images and Office documents). An unauthenticated attacker can POST arbitrary files of those types to a web-accessible directory and read them back over HTTP: malware/phishing hosting on the trusted domain and storage/disk abuse (default 500MB per file). It becomes remote code execution on any host that executes secondary file extensions (Apache AddHandler/mod_mime), or if an administrator has added an executable type (php/phtml) to the allowed list. Confirmed exploitable live (unauthenticated upload plus public read-back) on a default install. As of 2026-07-17 no fixed release is published (4.1.5 is current); the vendor's prepared fix removes the handler and the residual test_uploads directory on update. Mitigation until then: delete administrator/components/com_jdownloads/assets/upload/upload-handler.php and the administrator/components/com_jdownloads/test_uploads/ directory if present, or block web access to that path.

Is my site affected?

Affected
jDownloads from 4.1.0 up to and including 4.1.5
Fixed in
A release after 4.1.5
What to do
Update jDownloads to the newest release from the vendor. This flaw covers versions up to 4.1.5, so any later release is outside it.
Check whether your sites are affected

How CVE-2026-61900 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.

10.0 Critical

CVSS 4.0, scored by Joomla CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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: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: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

Timeline

  1. 17 July 2026mySites.guru check added for jDownloads (from 4.1.0 up to and including 4.1.5)
  2. 20 July 2026CVE-2026-61900 record published by its CNA

Rule details

Other vulnerabilities in jDownloads

Updating for CVE-2026-61900 alone can leave a site on a release another rule still matches. These are the other flaws we check for in the same extension.

jDownloads

Latest safe version: 4.1.6

References

CVE-2026-61900 questions

Which versions are affected by CVE-2026-61900?
CVE-2026-61900 affects jDownloads from 4.1.0 up to and including 4.1.5.
How do I fix CVE-2026-61900?
Update jDownloads to the newest release from the vendor. This flaw covers versions up to 4.1.5, so any later release is outside it.
How severe is CVE-2026-61900?
Joomla CNA scores it 10.0 (Critical) 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?

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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.