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.