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.Referenceshttps://phabricator.wikimedia.org/T297570https://gerrit.wikimedia.org/r/q/I37ece1dfdc80d38055067c9c4fa73ba591acd8bdhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7JNQA53K675TQBBJPZRAG5ZT6XES3IS/
