CreateWiki is Miraheze's MediaWiki extension for requesting & creating wikis. It is possible for users with (delete) or (suppressrevision) on any wiki in the farm to access suppressed wiki requests by going to the request's entry on Special:RequestWikiQueue on the wiki where they have these rights. The same vulnerability was present briefly on the REST API before being quickly corrected in commit `6bc0685`. To our knowledge, the vulnerable commits of the REST API are not running in production anywhere. This vulnerability is fixed in 23415c17ffb4832667c06abcf1eadadefd4c8937.
https://issue-tracker.miraheze.org/T11999
https://issue-tracker.miraheze.org/F3093343
https://github.com/miraheze/mw-config/commit/fb3e68bcef459e9cf2a415241b28042a6c9727e8
https://github.com/miraheze/CreateWiki/security/advisories/GHSA-4rcf-3cj2-46mq