An issue was discovered in MediaWiki before 1.35.8, 1.36.x and 1.37.x before 1.37.5, and 1.38.x before 1.38.3. Upon an action=rollback operation, the alreadyrolled message can leak a user name (when the user has been revision deleted/suppressed).
The Score extension through 0.3.0 for MediaWiki has a remote code execution vulnerability due to improper sandboxing of the GNU LilyPond executable. This allows any user with an ability to edit articles (potentially including unauthenticated anonymous users) to execute arbitrary Scheme or shell code by using crafted {{Image data to generate musical scores containing malicious code.
An issue was discovered in the VisualEditor extension in MediaWiki before 1.31.13, and 1.32.x through 1.35.x before 1.35.2. . When using VisualEditor to edit a MediaWiki user page belonging to an existing, but hidden, user, VisualEditor will disclose that the user exists. (It shouldn't because they are hidden.) This is related to ApiVisualEditor.
An issue was discovered in the GrowthExperiments extension for MediaWiki through 1.39.3. The UserImpactHandler for GrowthExperiments inadvertently returns the timezone preference for arbitrary users, which can be used to de-anonymize users.
An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. When a user with checkuserlog permissions makes many CheckUserLog API requests in some configurations, denial of service can occur (RequestTimeoutException or upstream request timeout).
An issue was discovered in the GrowthExperiments extension for MediaWiki through 1.39.3. Attackers might be able to see edits for which the username has been hidden, because there is no check for rev_deleted.
An issue was discovered in MediaWiki before 1.35.10, 1.36.x through 1.38.x before 1.38.6, and 1.39.x before 1.39.3. An auto-block can occur for an untrusted X-Forwarded-For header.
A vulnerability classified as problematic has been found in DaSchTour matomo-mediawiki-extension up to 2.4.2 on MediaWiki. This affects an unknown part of the file Piwik.hooks.php of the component Username Handler. The manipulation leads to cross site scripting. It is possible to initiate the attack remotely. The complexity of an attack is rather high. The exploitability is told to be difficult. The exploit has been disclosed to the public and may be used. Upgrading to version 2.4.3 is able to address this issue. The patch is named 681324e4f518a8af4bd1f93867074c728eb9923d. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220203.
An issue was discovered in the CheckUser extension for MediaWiki through 1.39.x. Various components of this extension can expose information on the performer of edits and logged actions. This information should not allow public viewing: it is supposed to be viewable only by users with suppression rights.
An issue was discovered in MediaWiki before 1.35.9, 1.36.x through 1.38.x before 1.38.5, and 1.39.x before 1.39.1. There is XSS in Wikibase date formatting via wikibase-time-precision-* fields. This allows JavaScript execution by staff/admin users who do not intentionally have the editsitejs capability.