An issue was discovered in includes/page/Article.php in MediaWiki 1.36.x through 1.39.x before 1.39.5 and 1.40.x before 1.40.1. Deleted revision existence is leaked due to incorrect permissions being checked. This reveals that a given revision ID belonged to the given page title, and its timestamp, both of which are not supposed to be public information.
{
"versions": [
{
"introduced": "1.36.0"
},
{
"fixed": "1.39.5"
},
{
"introduced": "0"
},
{
"last_affected": "1.40.0-NA"
}
]
}