It is possible to use action=mcrundo followed by action=mcrrestore to replace the content of any arbitrary page (that the user doesn't have edit rights for). This applies to any public wiki, or a private wiki that has at least one page set in $wgWhitelistRead.
Created mediawiki tracking bugs for this issue:
Affects: fedora-all [bug 2036703]
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):