Wikimedia Foundation MediaWiki Version Compare Extension Cross-Site Scripting Vulnerability

A cross-site scripting (XSS) vulnerability has been identified in the Wikimedia Foundation MediaWiki Version Compare Extension, affecting versions 1.39 through 1.43. This issue arises from improper encoding or escaping of output, which can be exploited to inject malicious scripts.

Impact

Exploitation of this vulnerability allows for cross-site scripting, where an attacker can inject malicious scripts that are executed in the context of the user's browser.

Reproduction

To reproduce this vulnerability, upload a crafted JSON file containing malicious scripts into fields such as 'wikiid', 'servername', 'generator', and 'name' of an extension. Then, set specific system messages to include additional scripts. Finally, navigate to the Special:VersionCompare page, input a wiki's API URL and the URL of the uploaded file, and submit the form.

Remediation

Users can update to Version Compare Extension versions 1.39.12, 1.42.6, or 1.43.1, where this vulnerability has been addressed.