Description
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.)
Remediation
References
Related Vulnerabilities
WordPress Plugin RSS Post Importer Cross-Site Scripting (2.2.1)
WordPress 5.6.x Multiple Vulnerabilities (5.6 - 5.6.2)
WordPress Plugin Sell Media Cross-Site Request Forgery (2.5.5)
Jboss EAP Deserialization of Untrusted Data Vulnerability (CVE-2019-16943)
WordPress Plugin User Meta Manager Information Disclosure (3.4.7)