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fetchmail-SA-2005-03: security announcement

Topics:		#1 crash retrieving headerless message in multidrop mode
		#2 fetchmail 6.2.5.X end of life

Author:		Matthias Andree
Version:	1.00
Announced:	2005-12-19
Type:		null pointer dereference
Impact:		fetchmail crashes
Danger:		low
Credits:	Daniel Drake, Gentoo (bug report)
		Sunil Shetye (bug fix)
CVE Name:	CVE-2005-4348
URL:		http://fetchmail.berlios.de/fetchmail-SA-2005-03.txt
		http://article.gmane.org/gmane.mail.fetchmail.user/7573
		http://bugs.debian.org/343836
Project URL:	http://fetchmail.berlios.de/

Affects:	fetchmail version 6.2.5.4
		fetchmail version 6.3.0

Not affected:	fetchmail 6.3.1
		fetchmail 6.2.5.5
		other versions not mentioned here or in the previous
		sections have not been checked

Corrected:	2005-12-19 - released fetchmail 6.3.1
		2005-12-18 - released fetchmail 6.3.1-rc1
		2005-12-19 - released fetchmail 6.2.5.5


0. Release history
==================

2005-12-19	1.00 - initial version


1. Background
=============

fetchmail is a software package to retrieve mail from remote POP2, POP3,
IMAP, ETRN or ODMR servers and forward it to local SMTP, LMTP servers or
message delivery agents.

fetchmail ships with a graphical, Python/Tkinter based configuration
utility named "fetchmailconf" to help the user create configuration (run
control) files for fetchmail.


2. Problem description and Impact
=================================

Fetchmail contains a bug that causes an application crash when fetchmail
is configured for multidrop mode and the upstream mail server sends a
message without headers.  As fetchmail does not record this message as
"previously fetched", it will crash with the same message if it is
re-executed, so it cannot make progress. A malicious or broken-into
upstream server could thus cause a denial of service in fetchmail
clients.

Note that such messages are not RFC-822 conformant, so if the server has
not been tampered with, the server software is faulty.


3. Workaround
=============

Where possible, singledrop mode may be an alternative.

For sites, where multidrop mode is required, no workaround is known.


4. Solution
===========

Download and install fetchmail 6.3.1 or a newer stable release from
fetchmail's project site at
<http://developer.berlios.de/project/showfiles.php?group_id=1824>.

The fix has also been backported to the 6.2.5.5 legacy release which is
available from the same site.

Note however that 6.3.X has very few incompatible changes since 6.2.5.X
so 6.3.X should be viable for most sites.  It is therefore recommended
that every user and distributor upgrade to 6.3.1 or newer.


5. End of life announcement
===========================

The fetchmail 6.2.5.X branch will be discontinued early in 2006.

The new 6.3.X stable branch has been available since 2005-11-30
and will not change except for bugfixes, documentation and translations.


A. Copyright, License and Warranty
==================================

(C) Copyright 2005 by Matthias Andree, <matthias.andree@gmx.de>.
Some rights reserved.

This work is licensed under the Creative Commons
Attribution-NonCommercial-NoDerivs German License. To view a copy of
this license, visit http://creativecommons.org/licenses/by-nc-nd/2.0/de/
or send a letter to Creative Commons; 559 Nathan Abbott Way;
Stanford, California 94305; USA.

THIS WORK IS PROVIDED FREE OF CHARGE AND WITHOUT ANY WARRANTIES.
Use the information herein at your own risk.

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