imap/nntpd.c in the NNTP server (nntpd) for Cyrus IMAPd 2.4.x before 2.4.12 allows remote attackers to bypass authentication by sending an AUTHINFO USER command without sending an additional AUTHINFO PASS command.

Multiple integer signedness errors in the NTLM implementation in Atrium MERCUR IMAPD (mcrimap4.exe) 5.00.14, with SP4, allow remote attackers to execute arbitrary code via a long NTLMSSP argument that triggers a stack-based buffer overflow.

Stack-based buffer overflow in Atrium MERCUR IMAPD allows remote attackers to have an unknown impact via a certain SUBSCRIBE command.

Stack-based buffer overflow in pop3d in Cyrus IMAPD (cyrus-imapd) 2.3.2, when the popsubfolders option is enabled, allows remote attackers to execute arbitrary code via a long USER command.

Buffer overflow in MailEnable Imapd (MEIMAP.exe) allows remote attackers to execute arbitrary code via a long LOGIN command.

Multiple buffer overflows in Cyrus IMAPd before 2.2.11 may allow attackers to execute arbitrary code via (1) an off-by-one error in the imapd annotate extension, (2) an off-by-one error in "cached header handling," (3) a stack-based buffer overflow in fetchnews, or (4) a stack-based buffer overflow in imapd.

Buffer overflows in Washington University imapd 2000a through 2000c could allow local users without shell access to execute code as themselves in certain configurations.

IMAP 4.1 BETA, and possibly other versions, does not properly handle the SIGABRT (abort) signal, which allows local users to crash the server (imapd) via certain sequences of commands, which causes a core dump that may contain sensitive password information.