It is possible to use action=edit&undo= followed by action=mcrundo and action=mcrrestore to view private pages on a private wiki that has at least one page set in $wgWhitelistRead.
Created mediawiki tracking bugs for this issue:
Affects: fedora-all [bug 2036699]
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):