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.
{ "versions": [ { "introduced": "0" }, { "last_affected": "1.37" } ] }
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-45472.json"
[ { "events": [ { "introduced": "0" }, { "last_affected": "35" } ] } ]