CVE-2026-76604 in Fabrik Extension
Summary
by MITRE • 08/22/2026
Joomla Extension - fabrikar.com - Unauthenticated remote code execution via PHP form element in Fabrik < 4.7.3 - The PHP form element is vulnerable to the execution of user provided codes.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified within Joomla extensions hosted on fabrikar.com, specifically affecting versions of Fabrik prior to 4.7.3, represents a critical security flaw classified as an unauthenticated remote code execution (RCE) via PHP form elements. This issue stems from insufficient input validation and sanitization mechanisms inherent in the way the application processes user-supplied data within its dynamic form generation capabilities. The core of the problem lies in the PHP form element type, which is designed to allow developers to embed custom PHP logic directly into forms for advanced functionality such as conditional visibility or complex calculations. However, when this feature interacts with untrusted input without proper safeguards, it creates a direct pathway for attackers to inject malicious code that executes on the server side during the rendering of the form.
From a technical perspective, the flaw allows an attacker to supply specially crafted data through standard web forms or API endpoints associated with Fabrik components. Because the vulnerability is unauthenticated, there are no access controls required to exploit it; any anonymous user interacting with the vulnerable instance can trigger the code execution. The mechanism typically involves manipulating form submission parameters where the application attempts to evaluate PHP expressions based on user input. If the framework fails to strictly validate that the input consists only of expected data types or whitelisted functions, an attacker can inject arbitrary PHP commands. These commands are then executed in the context of the web server process, granting the attacker a high degree of control over the underlying system infrastructure hosting the Joomla installation.
The operational impact of this vulnerability is severe and potentially catastrophic for affected organizations. Successful exploitation allows attackers to achieve full remote code execution on the target server. This capability enables a wide range of malicious activities including but not limited to data exfiltration, where sensitive user information or proprietary business data can be stolen; defacement of the website by modifying public-facing content; installation of web shells for persistent access; and pivoting into internal networks if the compromised server is part of a larger infrastructure. The lack of authentication requirements significantly lowers the barrier to entry for attackers, making this vulnerability highly attractive in automated scanning campaigns that target common CMS platforms like Joomla with known vulnerable plugins or extensions.
This incident aligns closely with CWE-94 Improper Control of Generation of Code (Code Injection) and specifically relates to CWE-78 Improper Neutralization of Special Elements used in an OS Command if the PHP execution leads to system-level commands, though primarily it is a code injection within the application logic layer. In terms of the MITRE ATT&CK framework, this vulnerability facilitates techniques associated with Initial Access via Web Applications and Execution through Application Layer Protocols or Scripting Interpreters like PHP. The unauthenticated nature places it firmly in the context of attacks that do not require prior compromise of user credentials, increasing its risk profile significantly compared to authenticated-only vulnerabilities.
Mitigation strategies must prioritize immediate remediation by updating the Fabrik extension to version 4.7.3 or later where these input validation issues have been addressed by the developers. Until an update is applied, administrators should consider disabling the PHP form element feature if it is not strictly necessary for business operations, thereby removing the attack vector entirely. Additionally, implementing a Web Application Firewall (WAF) with rules specifically tuned to detect and block common code injection patterns in POST requests can provide a layer of defense against exploitation attempts. Regular security audits and penetration testing focused on input validation across all custom forms are also recommended to ensure that similar vulnerabilities do not exist elsewhere within the application logic or other third-party extensions integrated into the Joomla environment.