ApprovedRevs: Stored Cross-Site Scripting (XSS) via unsanitized system messages

The ApprovedRevs extension for MediaWiki is vulnerable to stored XSS in multiple locations where system messages are inserted into raw HTML without proper escaping. Attackers can exploit this by injecting JavaScript payloads via the uselang=x-xss language override, which causes crafted message keys to be rendered unescaped. This issue affects Mediawiki - ApprovedRevs extension: from 1.39.X before 1.39.13, from 1.42.X before 1.42.7, from 1.43.X before 1.43.2.