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.
{
"cpes": [
"cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*"
],
"severity": "Medium"
}