Cross-site scripting (XSS) vulnerability in MediaWiki before 1.19.10, 1.2x before 1.21.4, and 1.22.x before 1.22.1 allows remote attackers to inject arbitrary web script or HTML via crafted XSL in an SVG file.
http://lists.wikimedia.org/pipermail/mediawiki-announce/2014-January/000138.html