An issue was discovered in MediaWiki 1.34.x before 1.34.4. On Special:Contributions, the NS filter uses unescaped messages as keys in the option key for an HTMLForm specifier. This is vulnerable to a mild XSS if one of those messages is changed to include raw HTML.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 57.3%