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Gentoo Linux Security Advisory                           GLSA 201701-74
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: libpng: Remote execution of arbitrary code
     Date: January 29, 2017
     Bugs: #604082
       ID: 201701-74

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Synopsis
=======
A null pointer dereference in libpng might allow remote attackers to
execute arbitrary code.

Background
=========
libpng is a standard library used to process PNG (Portable Network
Graphics) images. It is used by several programs, including web
browsers and potentially server processes.

Affected packages
================
    -------------------------------------------------------------------
     Package              /     Vulnerable     /            Unaffected
    -------------------------------------------------------------------
  1  media-libs/libpng            < 1.6.27                  >= 1.6.27
                                                            >= 1.5.28
                                                            >= 1.2.57

Description
==========
A null pointer dereference was discovered in libpng in the
png_push_save_buffer function.  In order to be vulnerable, an
application has to load a text chunk into the PNG structure, then
delete all text, then add another text chunk to the same PNG structure,
which seems to be an unlikely sequence, but it is possible.

Impact
=====
A remote attacker, by enticing a user to process a specially crafted
PNG file, could execute arbitrary code with the privileges of the
process.

Workaround
=========
There is no known workaround at this time.

Resolution
=========
All libpng 1.6.x users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=media-libs/libpng-1.6.27"

All libpng 1.5.x users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=media-libs/libpng-1.5.28:1.5"

All libpng 1.2.x users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=media-libs/libpng-1.2.57:1.2"

References
=========
[ 1 ] CVE-2016-10087
      http://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-10087

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

 https://security.gentoo.org/glsa/201701-74

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
https://bugs.gentoo.org.

License
======
Copyright 2017 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.

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