c-client IMAP Client, as used in imap-2002b and Pine 4.53, allows remote malicious IMAP servers to cause a denial of service (crash) and possibly execute arbitrary code via certain large (1) literal and (2) mailbox size values that cause either integer signedness errors or integer overflow errors.

POP2 or POP3 server (pop3d) in imap-uw IMAP package on FreeBSD and other operating systems creates lock files with predictable names, which allows local users to cause a denial of service (lack of mail access) for other users by creating lock files for other mail boxes.