An issue was discovered in MediaWiki before 1.31.13 and 1.32.x through 1.35.x before 1.35.2. When using the MediaWiki API to "protect" a page, a user is currently able to protect to a higher level than they currently have permissions for.
https://www.debian.org/security/2021/dsa-4889
https://security.gentoo.org/glsa/202107-40
https://phabricator.wikimedia.org/T270713
https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html