An issue was discovered in MediaWiki before 1.35.7, 1.36.x and 1.37.x before 1.37.3, and 1.38.x before 1.38.1. XSS can occur in configurations that allow a JavaScript payload in a username. After account creation, when it sets the page title to “Welcome” followed by the username, the username is not escaped: SpecialCreateAccount::successfulAction() calls ::showSuccessPage() with a message as second parameter, and OutputPage::setPageTitle() uses text().
lists.debian.org/debian-lts-announce/2022/09/msg00027.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7N5ZBWLNNPZKFK7Q4KEHGCJ2YELQEUJP/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DKKOQXPYLMBSEVDHFS32BPBR3ZQJKY5B/
phabricator.wikimedia.org/T308471
security.gentoo.org/glsa/202305-24
www.debian.org/security/2022/dsa-5246