An issue was discovered in the Wikibase extension for MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. During item merging, ItemMergeInteractor does not have an edit filter running (e.g., AbuseFilter).
An issue was discovered in the ProofreadPage extension for MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. XSS can occur via formatNumNoSeparators.
An issue was discovered in the SportsTeams extension for MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. It does not check for the anti-CSRF edit token in Special:SportsTeamsManager and Special:UpdateFavoriteTeams.
An issue was discovered in the PageTriage extension for MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. Usernames of hidden users are exposed.
An issue was discovered in ApiPageSet.php in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. It allows attackers to cause a denial of service (unbounded loop and RequestTimeoutException) when querying pages redirected to other variants with redirects and converttitles set.
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.
An issue was discovered in the CheckUser extension for MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. A user can use a rest.php/checkuser/v0/useragent-clienthints/revision/ URL to store an arbitrary number of rows in cu_useragent_clienthints, leading to a denial of service.
An issue was discovered in MediaWiki before 1.35.11, 1.36.x through 1.38.x before 1.38.7, 1.39.x before 1.39.4, and 1.40.x before 1.40.1. It is possible to bypass the Bad image list (aka badFile) by using the thumb parameter (aka Manualthumb) of the File syntax.
An issue was discovered in the CheckUserLog API in the CheckUser extension for MediaWiki through 1.39.3. There is incorrect access control for visibility of hidden users.
An issue was discovered in SubmitEntityAction in Wikibase in MediaWiki through 1.39.3. Because it doesn't use EditEntity for undo and restore, the intended interaction with AbuseFilter does not occur.