An issue was discovered in the CheckUser extension in MediaWiki before 1.35.14, 1.36.x through 1.39.x before 1.39.6, and 1.40.x before 1.40.2. XSS can occur via message definitions. e.g., in SpecialCheckUserLog.
{
"versions": [
{
"introduced": "0"
},
{
"fixed": "1.35.14"
},
{
"introduced": "1.36.0"
},
{
"fixed": "1.39.6"
},
{
"introduced": "1.40.0"
},
{
"fixed": "1.40.2"
}
]
}