An issue was discovered in the OATHAuth extension in MediaWiki before 1.31.10 and 1.32.x through 1.34.x before 1.34.4. For Wikis using OATHAuth on a farm/cluster (such as via CentralAuth), rate limiting of OATH tokens is only done on a single site level. Thus, multiple requests can be made across many wikis/sites concurrently.

An issue was discovered in MediaWiki before 1.31.10 and 1.32.x through 1.34.x before 1.34.4. The non-jqueryMsg version of mw.message().parse() doesn't escape HTML. This affects both message contents (which are generally safe) and the parameters (which can be based on user input). (When jqueryMsg is loaded, it correctly accepts only whitelisted tags in message contents, and escapes all parameters. Situations with an unloaded jqueryMsg are rare in practice, but can for example occur for Special:SpecialPages on a wiki with no extensions installed.)

An information leak was discovered in MediaWiki before 1.31.10 and 1.32.x through 1.34.x before 1.34.4. Handling of actor ID does not necessarily use the correct database or correct wiki.

In MediaWiki before 1.31.10 and 1.32.x through 1.34.x before 1.34.4, Special:UserRights exposes the existence of hidden users.

XSS exists in the MobileFrontend extension for MediaWiki before 1.34.4 because section.line is mishandled during regex section line replacement from PageGateway. Using crafted HTML, an attacker can elicit an XSS attack via jQuery's parseHTML method, which can cause image callbacks to fire even without the element being appended to the DOM.

An issue was discovered in the FileImporter extension for MediaWiki before 1.34.4. An attacker can import a file even when the target page is protected against "page creation" and the attacker should not be able to create it. This occurs because of a mishandled distinction between an upload restriction and a create restriction. An attacker cannot leverage this to overwrite anything, but can leverage this to force a wiki to have a page with a disallowed title.

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.

In MediaWiki before 1.31.8, 1.32.x and 1.33.x before 1.33.4, and 1.34.x before 1.34.2, private wikis behind a caching server using the img_auth.php image authorization security feature may have had their files cached publicly, so any unauthorized user could view them. This occurs because Cache-Control and Vary headers were mishandled.

resources/src/mediawiki.page.ready/ready.js in MediaWiki before 1.35 allows remote attackers to force a logout and external redirection via HTML content in a MediaWiki page.

The CentralAuth extension through REL1_34 for MediaWiki allows remote attackers to obtain sensitive hidden account information via an api.php?action=query&meta=globaluserinfo&guiuser= request. In other words, the information can be retrieved via the action API even though access would be denied when simply visiting wiki/Special:CentralAuth in a web browser.