DISPUTED postfixgroups.pl in Postfix 2.5.2 allows local users to overwrite arbitrary files via a symlink attack on the (1) /tmp/postfixgroups.stdout, (2) /tmp/postfixgroups.stderr, and (3) /tmp/postfixgroups.message temporary files. NOTE: the vendor disputes this vulnerability, stating "This is not a real issue ... users would have to edit a script under /usr/lib to enable it."

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.