In Dovecot before 2.3.10.1, a crafted SMTP/LMTP message triggers an unauthenticated use-after-free bug in submission-login, submission, or lmtp, and can lead to a crash under circumstances involving many newlines after a command.
In Dovecot before 2.3.9.2, an attacker can crash a push-notification driver with a crafted email when push notifications are used, because of a NULL Pointer Dereference. The email must use a group address as either the sender or the recipient.
In Dovecot before 2.2.36.4 and 2.3.x before 2.3.7.2 (and Pigeonhole before 0.5.7.2), protocol processing can fail for quoted strings. This occurs because '\0' characters are mishandled, and can lead to out-of-bounds writes and remote code execution.