CVE-2015-2938 in MediaWiki
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in MediaWiki before 1.19.24, 1.2x before 1.23.9, and 1.24.x before 1.24.2 allows remote attackers to inject arbitrary web script or HTML via a custom JavaScript file, which is not properly handled when previewing the file.
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Analysis
by VulDB Data Team • 05/03/2022
The CVE-2015-2938 vulnerability represents a critical cross-site scripting flaw in MediaWiki platforms that affected multiple version branches including 1.19.x, 1.23.x, and 1.24.x prior to their respective security patches. This vulnerability resides within the MediaWiki content management system's handling of custom JavaScript files during preview operations, creating a persistent security risk for organizations relying on this platform for collaborative documentation and knowledge management. The flaw specifically manifests when the system processes user-provided JavaScript content without adequate sanitization, allowing malicious actors to inject harmful scripts that can execute in the context of other users' browsers.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within MediaWiki's preview functionality for custom JavaScript files. When administrators or users attempt to preview JavaScript code that has been uploaded or referenced within the system, the application fails to properly sanitize the input before rendering it in the browser environment. This oversight creates an XSS attack vector where attackers can embed malicious JavaScript payloads within seemingly legitimate files, which then execute when other users view the preview. The vulnerability is categorized under CWE-79 as a failure to sanitize user input, specifically manifesting as a reflected cross-site scripting vulnerability that operates through the preview mechanism rather than direct user input fields.
The operational impact of CVE-2015-2938 extends beyond simple script injection, potentially enabling attackers to perform session hijacking, steal user credentials, redirect victims to malicious sites, or execute arbitrary commands on affected systems. Given that MediaWiki is widely deployed in enterprise environments, educational institutions, and government organizations for collaborative content management, the exploitation of this vulnerability could compromise sensitive organizational data and user privacy. The attack surface is particularly concerning because it operates through legitimate preview functionality that users would naturally expect to work without security concerns, making detection and prevention more challenging. Security researchers have classified this vulnerability as high-risk due to its potential for privilege escalation and the ease with which attackers can craft malicious JavaScript payloads that bypass typical security controls.
Organizations should implement immediate mitigations including updating to patched versions of MediaWiki, specifically versions 1.19.24, 1.23.9, and 1.24.2, which contain proper input sanitization and output encoding mechanisms. System administrators should also consider implementing additional security measures such as content security policy headers, input validation at multiple layers, and restricting JavaScript file uploads to trusted administrators only. The vulnerability demonstrates the importance of proper input validation and output encoding in web applications, aligning with ATT&CK technique T1566.001 for credential access through social engineering and T1588.001 for development tools and libraries. Organizations should also conduct regular security assessments of their MediaWiki installations and implement monitoring for suspicious file upload activities to detect potential exploitation attempts.