Postfix MTA updated to fix security vulnerabilities such as incorrectly checks the ownership of a mailbox. In some configurations, this allows for appending data to arbitrary files as root. This update has been rated as having moderate security impact.
All users of postfix should upgrade to these updated packages.
How do I patch Postfix under Debian / Ubuntu Linux?
First, update the internal database, enter:
# apt-get update
Install corrected Postfix package, enter:
# apt-get upgrade
How do I patch Postfix under RHEL / CentOS Linux?
Type the following command under RHEL / CentOS 5.x:
# yum update
Type the following command under RHEL <= 4.x:
# up2date -u