Postfix: Denial of Service

Security Team  Contact Address

Updated September 19, 2008

1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200809-09 / postfix
Release Date September 19, 2008
Latest Revision September 19, 2008: 01
Impact normal
Exploitable local
Package Vulnerable versions Unaffected versions Architecture(s)
mail-mta/postfix < 2.4.9, < 2.5.5 >= 2.4.9, >= 2.5.5 All supported architectures

Related bugreports: #236453

Synopsis

A memory leak in Postfix might allow local users to cause a Denial of Service.

2.  Impact Information

Background

Postfix is Wietse Venema's mailer that attempts to be fast, easy to administer, and secure, as an alternative to the widely-used Sendmail program.

Description

It has been discovered than Postfix leaks an epoll file descriptor when executing external commands, e.g. user-controlled $HOME/.forward or $HOME/.procmailrc files. NOTE: This vulnerability only concerns Postfix instances running on Linux 2.6 kernels.

Impact

A local attacker could exploit this vulnerability to reduce the performance of Postfix, and possibly trigger an assertion, resulting in a Denial of Service.

3.  Resolution Information

Workaround

Allow only trusted users to control delivery to non-Postfix commands.

Resolution

All Postfix 2.4 users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-mta/postfix-2.4.9"

All Postfix 2.5 users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-mta/postfix-2.5.5"

4.  References