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.
http://www.securityfocus.com/archive/1/430302/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2005-114.html