An issue was discovered in Cyrus IMAP before 3.12.4. There is a VPATCH BYPARAM double-free. An authenticated calendar user could crash a Cyrus CalDAV worker with a PATCH containing PATCH-ACTION="BYPARAM@..." against a resource with two or more properties of the matched kind. The memory holding the selector would be freed once on each iteration over the properties.

An issue was discovered in Cyrus IMAP before 3.12.4. CalDAV/CardDAV multiget bypasses a per-href ACL. An authenticated DAV user with some shared access to another user's calendar or address book could read even unshared events or contacts by including the target hrefs in a calendar-multiget or addressbook-multiget REPORT.

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. There is an ESEARCH cross-user content oracle. By using the ESEARCH command, an authenticated IMAP user could enumerate folder names under any account they could name. Search would return UIDs of messages matching the search, creating a content oracle (without allowing arbitrary reads of the target's content).