In MediaWiki before 1.34.1, users can add various Cascading Style Sheets (CSS) classes (which can affect what content is shown or hidden in the user interface) to arbitrary DOM nodes via HTML content within a MediaWiki page. This occurs because jquery.makeCollapsible allows applying an event handler to any Cascading Style Sheets (CSS) selector. There is no known way to exploit this for cross-site scripting (XSS).
In the GlobalBlocking extension before 2020-03-10 for MediaWiki through 1.34.0, an issue related to IP range evaluation resulted in blocked users re-gaining escalated privileges. This is related to the case in which an IP address is contained in two ranges, one of which is locally disabled.
The Scribunto extension for MediaWiki allows remote attackers to obtain the rollback token and possibly other sensitive information via a crafted module, related to unstripping special page HTML.
MediaWiki through 1.33.1 allows attackers to bypass the Title_blacklist protection mechanism by starting with an arbitrary title, establishing a non-resolvable redirect for the associated page, and using redirect=1 in the action API when editing that page.
MediaWiki through 1.32.1 has Incorrect Access Control. Suppressed username or log in Special:EditTags are exposed. Fixed in 1.32.2, 1.31.2, 1.30.2 and 1.27.6.
Wikimedia MediaWiki through 1.32.1 has Incorrect Access Control. Suppressed log in RevisionDelete page is exposed. Fixed in 1.32.2, 1.31.2, 1.30.2 and 1.27.6.
An Incorrect Access Control vulnerability was found in Wikimedia MediaWiki 1.18.0 through 1.32.1. It is possible to bypass the limits on IP range blocks ($wgBlockCIDRLimit) by using the API. Fixed in 1.32.2, 1.31.2, 1.30.2 and 1.27.6.
Wikimedia MediaWiki 1.23.0 through 1.32.1 has an information leak. Privileged API responses that include whether a recent change has been patrolled may be cached publicly. Fixed in 1.32.2, 1.31.2, 1.30.2 and 1.27.6.