Published: 12 September 2008
Postfix 2.4 before 2.4.9, 2.5 before 2.5.5, and 2.6 before 2.6-20080902, when used with the Linux 2.6 kernel, leaks epoll file descriptors during execution of "non-Postfix" commands, which allows local users to cause a denial of service (application slowdown or exit) via a crafted command, as demonstrated by a command in a .forward file.
From the Ubuntu security team
Wietse Venema discovered that Postfix leaked internal file descriptors when executing non-Postfix commands. A local attacker could exploit this to cause Postfix to run out of descriptors, leading to a denial of service.