CVE-2026-61424: DJ-Classifieds Joomla Extension RCE Flaw

CVE-2026-61424 Overview

CVE-2026-61424 is an unauthenticated arbitrary file upload vulnerability affecting the DJ-Classifieds Joomla extension prior to version 3.11.2. The flaw allows remote attackers to upload arbitrary files without authentication, leading to full remote code execution (RCE) on the underlying web server. The vulnerability is classified under [CWE-434] Unrestricted Upload of File with Dangerous Type. Any Joomla site running a vulnerable version of DJ-Classifieds is exposed to complete compromise through a network-based attack requiring no user interaction.

Critical Impact
Unauthenticated remote attackers can upload arbitrary files, including web shells, to gain full remote code execution and take over the affected Joomla website.

Affected Products

DJ-Classifieds Joomla extension versions prior to 3.11.2
Joomla installations bundling DJ-Classifieds from dj-extensions.com
Web servers hosting Joomla sites with the vulnerable extension enabled

Discovery Timeline

2026-07-20 - CVE-2026-61424 published to NVD
2026-07-23 - Last updated in NVD database

Technical Details for CVE-2026-61424

Vulnerability Analysis

The DJ-Classifieds extension exposes a file upload endpoint that fails to enforce authentication and does not properly validate file types or extensions before writing content to disk. An attacker can send a crafted HTTP request containing an executable payload, typically a PHP web shell, and have it stored in a web-accessible location on the server. Once uploaded, the attacker requests the file directly through the browser, causing the Joomla host to execute attacker-controlled code within the web server process context.

Successful exploitation grants the same privileges as the PHP process, which typically allows database access, credential theft, lateral movement, and persistence through additional web shells. The vulnerability affects confidentiality, integrity, and availability at the highest impact tier and can propagate to subsequent systems reachable from the compromised host.

Root Cause

The root cause is missing authentication combined with insufficient input validation in the file upload handler [CWE-434]. The extension does not verify the requester's session or role, does not enforce an allowlist of safe file extensions, and does not validate MIME types or file content signatures before persisting uploads to a public directory.

Attack Vector

Exploitation occurs over the network against the vulnerable Joomla site's public HTTP interface. The attacker submits a multipart file upload request to the DJ-Classifieds upload endpoint containing a PHP payload disguised or named as an executable script. After the file is stored under the Joomla web root, the attacker issues a follow-up HTTP GET request to execute the payload and establish interactive access. Detailed exploitation notes are described in the MySites Guru advisory.

Detection Methods for CVE-2026-61424

Indicators of Compromise

Unexpected .php, .phtml, or .phar files present in DJ-Classifieds upload directories such as images/, tmp/, or media/
HTTP POST requests to DJ-Classifieds upload endpoints originating from unauthenticated sessions
Web server logs showing GET requests to newly created files in extension upload folders
Outbound network connections from the PHP process to unfamiliar external hosts

Detection Strategies

Monitor web access logs for POST requests targeting DJ-Classifieds URLs followed by GETs to freshly written files
Deploy file integrity monitoring on the Joomla web root to flag newly created executable files
Inspect PHP process telemetry for spawned shell interpreters such as sh, bash, or cmd.exe

Monitoring Recommendations

Enable web application firewall (WAF) rules that block uploads with executable extensions to Joomla extension paths
Alert on any child process created by the web server user outside the expected baseline
Correlate authentication logs with upload activity to identify unauthenticated write operations

How to Mitigate CVE-2026-61424

Immediate Actions Required

Upgrade DJ-Classifieds to version 3.11.2 or later through the DJ-Extensions product page
Audit the Joomla web root for unauthorized .php files created since the extension was installed
Rotate all Joomla administrator credentials, database passwords, and API tokens if compromise is suspected
Temporarily disable the DJ-Classifieds extension if immediate patching is not possible

Patch Information

The vendor has released DJ-Classifieds version 3.11.2, which addresses the unauthenticated file upload flaw. Administrators should update through the Joomla Extension Manager or by downloading the package directly from dj-extensions.com. Verify the installed version under the Extensions Manager after upgrade to confirm remediation.

Workarounds

Restrict access to DJ-Classifieds upload endpoints using web server rules until the patch is applied
Configure the web server to deny execution of PHP files within extension upload directories
Place a WAF or reverse proxy in front of the Joomla instance to filter multipart uploads containing executable content

bash

# Apache configuration to deny PHP execution in DJ-Classifieds upload paths
<Directory "/var/www/joomla/images/com_djclassifieds">
    <FilesMatch "\.(php|phtml|phar|php3|php4|php5|php7)$">
        Require all denied
    </FilesMatch>
</Directory>