libremail is "a set of command line mail tools, it includes several clients, and allows to filter mails".
A format string vulnerability has been found in libremail's POP handling routines when the library has been set to run in DEBUG mode, the vulnerability can be exploited by remote attackers to cause the library to execute arbitrary code.
It could be exploited by tricking a user into connecting to a malicious POP server, or by sending a malicious mail (if the user reads it through a POP server), however it requires that debug mode is activated (not default setting).