CVE-2019-7740 in Joomla
Summary
by MITRE
An issue was discovered in Joomla! before 3.9.3. Inadequate parameter handling in JavaScript code (core.js writeDynaList) could lead to an XSS attack vector.
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Analysis
by VulDB Data Team • 07/10/2023
The vulnerability identified as CVE-2019-7740 represents a critical cross-site scripting flaw within the Joomla! content management system affecting versions prior to 3.9.3. This security weakness stems from insufficient input validation and sanitization practices within the core.js library, specifically within the writeDynaList function that handles dynamic list generation. The issue manifests when user-supplied parameters are not properly escaped or validated before being rendered in JavaScript contexts, creating opportunities for malicious actors to inject arbitrary script code that executes in the victim's browser session.
The technical implementation of this vulnerability resides in the JavaScript core.js file where the writeDynaList function processes dynamic content without adequate sanitization measures. When Joomla! generates dynamic dropdown lists or other interactive elements, the function accepts parameters that should be treated as untrusted input but are instead directly incorporated into the generated JavaScript code. This pattern violates fundamental security principles of input validation and output encoding, allowing attackers to craft malicious payloads that exploit the lack of proper parameter handling in the client-side code execution environment.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with potential access to user sessions and sensitive data within the Joomla! administrative interface. An attacker could leverage this XSS vector to steal cookies, hijack user sessions, or manipulate the CMS functionality to perform unauthorized actions. The vulnerability affects both frontend and backend contexts where dynamic lists are utilized, potentially compromising administrator accounts and enabling privilege escalation attacks. According to CWE classification, this represents a CWE-79: Cross-site Scripting vulnerability that specifically impacts the client-side execution environment through improper input handling.
Security practitioners should consider this vulnerability in the context of broader attack frameworks such as the ATT&CK matrix where client-side exploitation techniques are categorized under initial access and execution phases. The vulnerability demonstrates how seemingly benign JavaScript functionality can become a gateway for more sophisticated attacks when proper security controls are absent. Organizations running affected Joomla! versions face significant risk of unauthorized access and data compromise, particularly in environments where administrators interact with potentially malicious content or where user-generated content is not properly filtered.
Mitigation strategies for CVE-2019-7740 require immediate implementation of the official Joomla developers involved proper sanitization of parameters passed to the writeDynaList function and enhanced validation of dynamic content generation to prevent unauthorized script injection. Regular security monitoring and patch management procedures should be enforced to prevent similar vulnerabilities from emerging in other JavaScript components or third-party extensions that may interact with the core CMS functionality.