A new security update has been released for Gentoo Linux - libpng: Multiple vulnerabilities. Here the announcement:

Gentoo Linux Security Advisory GLSA 200903-28
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http://security.gentoo.org/
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Severity: Normal
Title: libpng: Multiple vulnerabilities
Date: March 15, 2009
Bugs: #244808, #255231, #259578
ID: 200903-28

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Synopsis
========

Multiple vulnerabilities were found in libpng, which might result in
the execution of arbitrary code

Background
==========

libpng is the official PNG reference library used to read, write and
manipulate PNG images.

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

-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 media-libs/libpng < 1.2.35 >= 1.2.35

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

Multiple vulnerabilities were discovered in libpng:

* A memory leak bug was reported in png_handle_tEXt(), a function
that is used while reading PNG images (CVE-2008-6218).

* A memory overwrite bug was reported by Jon Foster in
png_check_keyword(), caused by writing overlong keywords to a PNG
file (CVE-2008-5907).

* A memory corruption issue, caused by an incorrect handling of an
out of memory condition has been reported by Tavis Ormandy of the
Google Security Team. That vulnerability affects direct uses of
png_read_png(), pCAL chunk and 16-bit gamma table handling
(CVE-2009-0040).

Impact
======

A remote attacker may execute arbitrary code with the privileges of the
user opening a specially crafted PNG file by exploiting the erroneous
out-of-memory handling. An attacker may also exploit the
png_check_keyword() error to set arbitrary memory locations to 0, if
the application allows overlong, user-controlled keywords when writing
PNG files. The png_handle_tEXT() vulnerability may be exploited by an
attacker to potentially consume all memory on a users system when a
specially crafted PNG file is opened.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All libpng users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=media-libs/libpng-1.2.35"

References
==========

[ 1 ] CVE-2008-5907
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5907
[ 2 ] CVE-2008-6218
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-6218
[ 3 ] CVE-2009-0040
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0040

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

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

http://security.gentoo.org/glsa/glsa-200903-28.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 2009 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