Mutt before 1.14.4 and NeoMutt before 2020-06-19 have a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a man-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."
An issue was discovered in NeoMutt before 2018-07-16. newsrc.c does not properly restrict '/' characters that may have unsafe interaction with cache pathnames.
An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. imap/message.c has a stack-based buffer overflow for a FETCH response with a long INTERNALDATE field.
An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. imap_quote_string in imap/util.c does not leave room for quote characters, leading to a stack-based buffer overflow.
An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. They allow remote IMAP servers to execute arbitrary commands via backquote characters, related to the mailboxes command associated with a manual subscription or unsubscription.