An issue was discovered in MediaWiki before 1.35.5, 1.36.x before 1.36.3, and 1.37.x before 1.37.1. A denial of service (resource consumption) can be accomplished by searching for a very long key in a Language Name Search.
https://phabricator.wikimedia.org/T293749
https://gerrit.wikimedia.org/r/q/Ide32704cca578b9aecbce34bdcc0ac25c2a09a4d