An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. Users can bypass intended restrictions on deleting pages in certain "fast double move" situations. MovePage::isValidMoveTarget() uses FOR UPDATE, but it's only called if Title::getArticleID() returns non-zero with no special flags. Next, MovePage::moveToInternal() will delete the page if getArticleID(READ_LATEST) is non-zero. Therefore, if the page is missing in the replica DB, isValidMove() will return true, and then moveToInternal() will unconditionally delete the page if it can be found in the master.

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. Special:Contributions can leak that a "hidden" user exists.

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. ContentModelChange does not check if a user has correct permissions to create and set the content model of a nonexistent page.

An issue was discovered in MediaWiki before 1.31.13 and 1.32.x through 1.35.x before 1.35.2. When using the MediaWiki API to "protect" a page, a user is currently able to protect to a higher level than they currently have permissions for.

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. Blocked users are unable to use Special:ResetTokens. This has security relevance because a blocked user might have accidentally shared a token, or might know that a token has been compromised, and yet is not able to block any potential future use of the token by an unauthorized party.

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. On ChangesList special pages such as Special:RecentChanges and Special:Watchlist, some of the rcfilters-filter-* label messages are output in HTML unescaped, leading to XSS.

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. On Special:NewFiles, all the mediastatistics-header-* messages are output in HTML unescaped, leading to XSS.

The API in the Push extension for MediaWiki through 1.35 used cleartext for ApiPush credentials, allowing for potential information disclosure.

The API in the Push extension for MediaWiki through 1.35 did not require an edit token in ApiPushBase.php and therefore facilitated a CSRF attack.

The MediaWiki "Report" extension has a Cross-Site Request Forgery (CSRF) vulnerability. Before fixed version, there was no protection against CSRF checks on Special:Report, so requests to report a revision could be forged. The problem has been fixed in commit f828dc6 by making use of MediaWiki edit tokens.

An issue was discovered in the PushToWatch extension for MediaWiki through 1.35.1. The primary form did not implement an anti-CSRF token and therefore was completely vulnerable to CSRF attacks against onSkinAddFooterLinks in PushToWatch.php.

An issue was discovered in the Widgets extension for MediaWiki through 1.35.1. Any user with the ability to edit pages within the Widgets namespace could call any static function within any class (defined within PHP or MediaWiki) via a crafted HTML comment, related to a Smarty template. For example, a person in the Widget Editors group could use \MediaWiki\Shell\Shell::command within a comment.

An issue was discovered in the SecurePoll extension for MediaWiki through 1.35.1. The non-admin vote list contains a full vote timestamp, which may provide unintended clues about how a voting process unfolded.

An issue was discovered in the CasAuth extension for MediaWiki through 1.35.1. Due to improper username validation, it allowed user impersonation with trivial manipulations of certain characters within a given username. An ordinary user may be able to login as a "bureaucrat user" who has a similar username, as demonstrated by usernames that differ only in (1) bidirectional override symbols or (2) blank space.

An issue was discovered in the GlobalUsage extension for MediaWiki through 1.35.1. SpecialGlobalUsage.php calls WikiMap::makeForeignLink unsafely. The $page variable within the formatItem function was not being properly escaped, allowing for XSS under certain conditions.

An issue was discovered in MediaWiki before 1.35.1. Missing users (accounts that don't exist) and hidden users (accounts that have been explicitly hidden due to being abusive, or similar) that the viewer cannot see are handled differently, exposing sensitive information about the hidden status to unprivileged viewers. This exists on various code paths.

MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. Language::translateBlockExpiry itself does not escape in all code paths. For example, the return of Language::userTimeAndDate is is always unsafe for HTML in a month value. This affects MediaWiki 1.12.0 and later.

MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. MediaWiki:blanknamespace potentially can be output as raw HTML with SCRIPT tags via LogFormatter::makePageLink(). This affects MediaWiki 1.33.0 and later.

MediaWiki before 1.35.1 blocks legitimate attempts to hide log entries in some situations. If one sets MediaWiki:Mainpage to Special:MyLanguage/Main Page, visits a log entry on Special:Log, and toggles the "Change visibility of selected log entries" checkbox (or a tags checkbox) next to it, there is a redirection to the main page's action=historysubmit (instead of the desired behavior in which a revision-deletion form appears).

In MediaWiki before 1.35.1, the messages userrights-expiry-current and userrights-expiry-none can contain raw HTML. XSS can happen when a user visits Special:UserRights but does not have rights to change all userrights, and the table on the left side has unchangeable groups in it. (The right column with the changeable groups is not affected and is escaped correctly.)