Citizen is a MediaWiki skin that makes extensions part of the cohesive experience. All system messages in menu headings using the Menu.mustache template are inserted as raw HTML, allowing anybody who can edit those messages to insert arbitrary HTML into the DOM. This impacts wikis where a group has the `editinterface` but not the `editsitejs` user right. This vulnerability is fixed in 3.3.1.

starcitizentools/citizen-skin allows stored XSS in menu heading message