Mediawiki v1.40.0 does not validate namespaces used in XML files. Therefore, if the instance administrator allows XML file uploads, a remote attacker with a low-privileged user account can use this exploit to become an administrator by sending a malicious link to the instance administrator. (CVE-2023-3550) An issue was discovered in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. There is XSS in youhavenewmessagesmanyusers and youhavenewmessages i18n messages. This is related to MediaWiki:Youhavenewmessagesfromusers. (CVE-2023-45360) An issue was discovered in DifferenceEngine.php in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. diff-multi-sameuser (aka "X intermediate revisions by the same user not shown") ignores username suppression. This is an information leak. (CVE-2023-45362) An issue was discovered in ApiPageSet.php in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. It allows attackers to cause a denial of service (unbounded loop and RequestTimeoutException) when querying pages redirected to other variants with redirects and converttitles set. (CVE-2023-45363) An issue was discovered in includes/page/Article.php in MediaWiki 1.36.x through 1.39.x before 1.39.5 and 1.40.x before 1.40.1. Deleted revision existence is leaked due to incorrect permissions being checked. This reveals that a given revision ID belonged to the given page title, and its timestamp, both of which are not supposed to be public information. (CVE-2023-45364) An issue was discovered in MediaWiki before 1.35.14, 1.36.x through 1.39.x before 1.39.6, and 1.40.x before 1.40.2. In includes/logging/RightsLogFormatter.php, group-*-member messages can result in XSS on Special:log/rights. (CVE-2023-51704)