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Gentoo Linux Security Advisory                           GLSA 200710-16
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                                            http://security.gentoo.org/
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  Severity: High
     Title: X.Org X server: Composite local privilege escalation
      Date: October 14, 2007
      Bugs: #191964
        ID: 200710-16

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Synopsis
========

A vulnerability has been discovered in the Composite extension of the
X.Org X server, allowing for a local privilege escalation.

Background
==========

The X Window System is a graphical windowing system based on a
client/server model.

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

    -------------------------------------------------------------------
     Package               /   Vulnerable   /               Unaffected
    -------------------------------------------------------------------
  1  x11-base/xorg-server     < 1.3.0.0-r1               >= 1.3.0.0-r1

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

Aaron Plattner discovered a buffer overflow in the compNewPixmap()
function when copying data from a large pixel depth pixmap into a
smaller pixel depth pixmap.

Impact
======

A local attacker could execute arbitrary code with the privileges of
the user running the X server, typically root.

Workaround
==========

Disable the Composite extension by setting ' Option "Composite"
"disable" ' in the Extensions section of xorg.conf.

Note: This could affect the functionality of some applications.

Resolution
==========

All X.Org X server users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=x11-base/xorg-server-1.3.0.0-r1"

References
==========

  [ 1 ] CVE-2007-4730
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-4730

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

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

  http://security.gentoo.org/glsa/glsa-200710-16.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
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