The admin API module in the QuizGame extension for MediaWiki through 1.37.2 (before 665e33a68f6fa1167df99c0aa18ed0157cdf9f66) omits a check for the quizadmin user.
An XSS issue was discovered in MediaWiki before 1.35.6, 1.36.x before 1.36.4, and 1.37.x before 1.37.2. The widthheight, widthheightpage, and nbytes properties of messages are not escaped when used in galleries or Special:RevisionDelete.
In MediaWiki through 1.37, XSS can occur in Wikibase because an external identifier property can have a URL format that includes a $1 formatter substitution marker, and the javascript: URL scheme (among others) can be used.