Gentoo: w3m Format string vulnerability
Posted by Benjamin D. Thomas   
Gentoo w3m does not correctly handle format string specifiers in SSL certificates.
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Gentoo Linux Security Advisory                           GLSA 200701-06
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: w3m: Format string vulnerability
      Date: January 12, 2007
      Bugs: #159145
        ID: 200701-06

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Synopsis
========

w3m does not correctly handle format string specifiers in SSL
certificates.

Background
==========

w3m is a multi-platform text-based web browser.

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

    -------------------------------------------------------------------
     Package         /  Vulnerable  /                       Unaffected
    -------------------------------------------------------------------
  1  www-client/w3m     < 0.5.1-r4                         >= 0.5.1-r4

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

w3m in -dump or -backend mode does not correctly handle printf() format
string specifiers in the Common Name (CN) field of an X.509 SSL
certificate.

Impact
======

An attacker could entice a user to visit a malicious website that would
load a specially crafted X.509 SSL certificate containing "%n" or other
format string specifiers, possibly resulting in the execution of
arbitrary code with the rights of the user running w3m.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All w3m users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=www-client/w3m-0.5.1-r4"

References
==========

  [ 1 ] CVE-2006-6772
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-6772

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

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

  http://security.gentoo.org/glsa/glsa-200701-06.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