A new security update has been released for Gentoo Linux - Courier-IMAP: Remote execution of arbitrary code. Here the announcement:

Gentoo Linux Security Advisory GLSA 200704-18
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http://security.gentoo.org/
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Severity: High
Title: Courier-IMAP: Remote execution of arbitrary code
Date: April 22, 2007
Bugs: #168196
ID: 200704-18

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Synopsis
========

A vulnerability has been discovered in Courier-IMAP allowing for remote
code execution with root privileges.

Background
==========

Courier-IMAP is an IMAP server which is part of the Courier mail
system. It provides access only to maildirs.

Affected packages
=================

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Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 net-mail/courier-imap < 4.0.6-r2 >= 4.0.6-r2

Description
===========

CJ Kucera has discovered that some Courier-IMAP scripts don't properly
handle the XMAILDIR variable, allowing for shell command injection.

Impact
======

A remote attacker could send specially crafted login credentials to a
Courier-IMAP server instance, possibly leading to remote code execution
with root privileges.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All Courier-IMAP users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-mail/courier-imap-4.0.6-r2"

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-200704-18.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2007 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5