CVE-2024-29374 in Moodle
Summary
by MITRE • 03/21/2024
A Cross-Site Scripting (XSS) vulnerability exists in the way MOODLE 3.10.9 handles user input within the "GET /?lang=" URL parameter.
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Analysis
by VulDB Data Team • 04/13/2025
The vulnerability identified as CVE-2024-29374 represents a critical cross-site scripting flaw within Moodle version 3.10.9 that specifically affects the handling of user input through the GET parameter "lang=". This issue falls under the Common Weakness Enumeration category CWE-79 which defines improper neutralization of input during web page generation as a fundamental weakness in web application security. The vulnerability stems from inadequate sanitization of the language parameter that is processed during the application's initialization phase when determining the user interface language. When an attacker crafts a malicious URL containing crafted script code within the lang parameter, the application fails to properly escape or validate this input before rendering it in the web response, creating an avenue for malicious script execution in the context of the victim's browser session.
The technical exploitation of this vulnerability occurs when a user visits a maliciously crafted URL that includes script code within the lang parameter value. The vulnerable Moodle application processes this parameter without adequate input validation or output encoding, allowing the malicious payload to be embedded directly into the HTML response sent to the user's browser. This creates a persistent cross-site scripting vector where the attacker's script code executes within the victim's browser context with the privileges of the authenticated user. The vulnerability is particularly concerning because it affects the core language selection functionality that is invoked during every page load, making it easily exploitable through various attack vectors including phishing emails, malicious links in forums, or compromised third-party websites that redirect users to the vulnerable Moodle instance.
The operational impact of CVE-2024-29374 extends beyond simple script execution as it can lead to full account compromise and data exfiltration. Attackers can leverage this vulnerability to steal session cookies, perform actions on behalf of authenticated users, access sensitive course materials, modify user permissions, or redirect users to malicious websites. The attack surface is amplified by the fact that Moodle is widely deployed in educational institutions and corporate training environments where users frequently access the platform with elevated privileges. The vulnerability aligns with ATT&CK technique T1566.001 which describes the use of malicious links to deliver payloads, and T1071.001 which covers application layer protocol usage. Organizations running Moodle 3.10.9 are at risk of unauthorized access to learning management system data, potential data breaches, and compromise of user credentials across their entire user base.
Mitigation strategies for CVE-2024-29374 should prioritize immediate patching of the affected Moodle version to the latest security release which includes proper input validation and output encoding for the language parameter. System administrators should implement comprehensive input validation that strictly filters the lang parameter to only accept predefined, whitelisted language codes while rejecting any input containing script tags or suspicious characters. Additionally, organizations should deploy Content Security Policy (CSP) headers that restrict script execution and prevent the loading of external resources that could be used in XSS attacks. Network-based mitigations such as web application firewalls can provide additional protection layers, though these should not be considered a substitute for proper application-level fixes. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other input parameters and application components, with particular attention to areas where user input is processed and rendered without adequate sanitization. The vulnerability demonstrates the critical importance of input validation and output encoding practices that are fundamental to preventing XSS attacks across all web applications.