It was discovered that the Postfix package incorrectly granted write access
on the PID directory to the postfix user. A local attacker could use this
flaw to possibly conduct a symlink attack and overwrite arbitrary files.
This issue only affected Ubuntu 6.06 LTS and 8.04 LTS. (CVE-2009-2939)
Wietse Venema discovered that Postfix incorrectly handled cleartext
commands after TLS is in place. A remote attacker could exploit this to
inject cleartext commands into TLS sessions, and possibly obtain
confidential information such as passwords. (CVE-2011-0411)