CVE-2015-2933 in MediaWiki
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Html class 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 LanguageConverter substitution string when using a language variant.
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Analysis
by VulDB Data Team • 05/03/2022
The CVE-2015-2933 vulnerability represents a critical cross-site scripting flaw within MediaWiki's Html class implementation, affecting multiple version ranges including 1.19.23 and earlier, 1.23.8 and earlier in the 1.2x series, and 1.24.1 and earlier in the 1.24.x series. This vulnerability specifically targets the LanguageConverter substitution functionality that enables users to switch between different language variants of content, creating a pathway for remote attackers to execute malicious scripts within the context of other users' browsers. The flaw operates by failing to properly sanitize user-provided input during the processing of language variant substitutions, allowing attackers to inject malicious HTML or JavaScript code that gets rendered in the browser.
The technical exploitation of this vulnerability occurs when a malicious user creates content containing specially crafted LanguageConverter substitution strings that include script tags or other malicious payloads. When other users view this content, the MediaWiki application processes the substitution string without adequate input validation or output encoding, resulting in the execution of the injected code within the victim's browser context. This represents a classic server-side XSS vulnerability where the application fails to properly escape or validate user-supplied data before rendering it as part of the web page output. The vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications.
The operational impact of CVE-2015-2933 extends beyond simple script execution to potentially enable sophisticated attacks including session hijacking, credential theft, and privilege escalation within the MediaWiki environment. Attackers could leverage this vulnerability to steal user sessions, modify content, or even gain administrative privileges if they can target administrators or users with elevated permissions. The vulnerability affects not just individual users but entire MediaWiki installations, making it particularly dangerous for collaborative platforms where multiple users contribute content. The attack vector is particularly insidious because it can be embedded within legitimate-looking language variant content, making it difficult for users to detect malicious activity.
Organizations using affected MediaWiki versions should immediately implement the available patches and updates to remediate this vulnerability. The recommended mitigation strategy involves upgrading to the patched versions of MediaWiki, specifically 1.19.24, 1.23.9, or 1.24.2 respectively. Additionally, administrators should implement input validation measures and output encoding for all user-provided content, particularly around language variant handling. The vulnerability demonstrates the importance of proper data sanitization in web applications and aligns with ATT&CK technique T1566 which covers social engineering through malicious content delivery. Security monitoring should include detection of unusual LanguageConverter usage patterns and suspicious content submissions, as these may indicate exploitation attempts. Organizations should also consider implementing web application firewalls and content security policies to provide additional defense layers against similar XSS vulnerabilities.