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Gentoo Linux Security Advisory                           GLSA 200608-12
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                                            http://security.gentoo.org/
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  Severity: High
     Title: x11vnc: Authentication bypass in included LibVNCServer code
      Date: August 07, 2006
      Bugs: #142559
        ID: 200608-12

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Synopsis
========

VNC servers created with x11vnc accept insecure protocol types, even
when the server does not offer it, resulting in the possibility of
unauthorized access to the server.

Background
==========

x11vnc provides VNC servers for X displays.

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

    -------------------------------------------------------------------
     Package          /  Vulnerable  /                      Unaffected
    -------------------------------------------------------------------
  1  x11-misc/x11vnc       < 0.8.1                            >= 0.8.1

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

x11vnc includes vulnerable LibVNCServer code, which fails to properly
validate protocol types effectively letting users decide what protocol
to use, such as "Type 1 - None" (GLSA-200608-05). x11vnc will accept
this security type, even if it is not offered by the server.

Impact
======

An attacker could exploit this vulnerability to gain unauthorized
access with the privileges of the user running the VNC server.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All x11vnc users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=x11-misc/x11vnc-0.8.1"

References
==========

  [ 1 ] CVE-2006-2450
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2450
  [ 2 ] GLSA-200608-05
        http://www.gentoo.org/security/en/glsa/glsa-200608-05.xml

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

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

  http://security.gentoo.org/glsa/glsa-200608-12.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@g.o or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2006 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