CVE-2026-105603 in DJ-Classifieds Extension
Summary
by MITRE • 11/02/2026
Joomla Extension - dj-extensions.com - Authenticated arbitrary file upload in DJ-Classifieds < 3.11.3 - The Joomla extension DJ-Classifieds is vulnerable to an unprivileged file upload, leading to full RCE.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified within the DJ-Classifieds component for Joomla versions prior to 3.11.3 represents a critical security failure in input validation and access control mechanisms. This flaw allows authenticated users with minimal privileges, such as standard subscribers or contributors, to bypass intended restrictions on file uploads. In typical web application architectures, particularly content management systems like Joomla, the ability to upload files is often restricted based on user roles to prevent malicious actors from executing arbitrary code on the server. However, in this specific instance, the validation logic fails to adequately verify the integrity of uploaded files or restricts them only by file extension without sufficient sanitization of metadata or context. This oversight creates a pathway for an attacker to upload executable scripts disguised as legitimate media files, such as images with embedded PHP code or other server-side script formats that the web server may interpret and execute if placed in a writable directory accessible via HTTP requests.
From a technical perspective, this vulnerability is classified under CWE-434, which describes the unrestricted uploading of file types, often leading to remote code execution when combined with insufficient validation of file contents or destination directories. The operational impact of this flaw is severe, as it directly leads to Remote Code Execution (RCE). Once an attacker successfully uploads a malicious script and obtains its URL through the application's response mechanisms, they can trigger the execution of arbitrary commands on the underlying server infrastructure. This capability effectively grants the attacker full control over the compromised system, enabling them to exfiltrate sensitive data, modify website content, install backdoors for persistent access, or pivot into other parts of the internal network if the web server is not properly isolated. The severity is further amplified by the fact that authentication is required but only at a low privilege level, meaning that any registered user account can be leveraged to exploit this condition without needing administrative credentials.
In terms of threat intelligence and behavioral mapping, this vulnerability aligns with MITRE ATT&CK technique T1505.003, known as Web Shell: Server Script Upload. Attackers frequently utilize such upload flaws to deploy web shells that serve as persistent access mechanisms for subsequent exploitation phases. The lack of proper server-side validation allows the malicious payload to reside in a location where it can be invoked via standard HTTP requests, facilitating lateral movement and data theft. This pattern is consistent with many high-severity vulnerabilities found in popular CMS extensions where developers prioritize functionality over rigorous security auditing during development cycles.
To mitigate this risk, immediate action must be taken by upgrading the DJ-Classifieds extension to version 3.11.3 or later, which addresses these input validation deficiencies. Administrators should also enforce strict file type whitelisting on the server level rather than relying solely on application-level checks, ensuring that only non-executable media formats are accepted and stored in directories with execute permissions disabled. Additionally, implementing Web Application Firewall rules to detect common web shell patterns can provide an additional layer of defense against exploitation attempts while patches are being applied. Regular security audits and code reviews focusing on file handling routines are recommended to prevent similar vulnerabilities from arising in other components or future updates.