Description
An issue was discovered in MediaWiki before 1.31.10 and 1.32.x through 1.34.x before 1.34.4. The non-jqueryMsg version of mw.message().parse() doesn't escape HTML. This affects both message contents (which are generally safe) and the parameters (which can be based on user input). (When jqueryMsg is loaded, it correctly accepts only whitelisted tags in message contents, and escapes all parameters. Situations with an unloaded jqueryMsg are rare in practice, but can for example occur for Special:SpecialPages on a wiki with no extensions installed.)
Remediation
References
Related Vulnerabilities
Python Uncontrolled Resource Consumption Vulnerability (CVE-2021-3733)
XWiki Exposure of Resource to Wrong Sphere Vulnerability (CVE-2023-29208)
MediaWiki Improper Check for Unusual or Exceptional Conditions Vulnerability (CVE-2021-44856)
WordPress Other Vulnerability (CVE-2007-2821)
Jenkins Exposure of Sensitive Information to an Unauthorized Actor Vulnerability (CVE-2015-5317)