In MediaWiki through 1.33.0, Special:Redirect allows information disclosure of suppressed usernames via a User ID Lookup.
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7OMG3BMUHGWTAPYTK2NXM6CXF6FYLOUO/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QBAOLXETM5BOYQG6OQVHGB2LNLZUXVN6/
phabricator.wikimedia.org/T230402
seclists.org/bugtraq/2019/Oct/32
www.debian.org/security/2019/dsa-4545