Cyrus IMAP before 3.2.7, and 3.3.x and 3.4.x before 3.4.1, allows remote authenticated users to bypass intended access restrictions on server annotations and consequently cause replication to stall.
https://www.cyrusimap.org/imap/download/release-notes/3.4/x/3.4.1.html
https://www.cyrusimap.org/imap/download/release-notes/3.2/x/3.2.7.html
https://cyrus.topicbox.com/groups/announce/T126392718bc29d6b/cyrus-imap-3-2-7-released
https://cyrus.topicbox.com/groups/announce/T056901c106ecfce3/cyrus-imap-3-4-1-released