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.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. CheckUser TokenManager insecurely uses AES-CTR encryption with a repeated (aka re-used) nonce, allowing an adversary to decrypt.

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.

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. When installing with a pre-existing data directory that has weak permissions, the SQLite files are created with file mode 0644, i.e., world readable to local users. These files include credentials data.

In the GrowthExperiments extension for MediaWiki through 1.39, the growthmanagementorlist API allows blocked users (blocked in ApiManageMentorList) to enroll as mentors or edit any of their mentorship-related properties.

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. E-Widgets does widget replacement in HTML attributes, which can lead to XSS, because widget authors often do not expect that their widget is executed in an HTML attribute context.

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. SpecialMobileHistory allows remote attackers to cause a denial of service because database queries are slow.

A vulnerability was found in Wikimedia mediawiki-extensions-I18nTags and classified as problematic. This issue affects some unknown processing of the file I18nTags_body.php of the component Unlike Parser. The manipulation leads to cross site scripting. The attack may be initiated remotely. The identifier of the patch is b4bc3cbbb099eab50cf2b544cf577116f1867b94. It is recommended to apply a patch to fix this issue. The identifier VDB-217445 was assigned to this vulnerability.

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. When changes made by an IP address are reassigned to a user (using reassignEdits.php), the changes will still be attributed to the IP address on Special:Contributions when doing a range lookup.