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Gentoo Linux Security Advisory                           GLSA 200511-23
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                                            https://security.gentoo.org/
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  Severity: Normal
     Title: chmlib, KchmViewer: Stack-based buffer overflow
      Date: November 28, 2005
      Bugs: #110557
        ID: 200511-23

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Synopsis
=======
chmlib and KchmViewer contain a buffer overflow vulnerability which may
lead to the execution of arbitrary code.

Background
=========
chmlib is a library for dealing with Microsoft ITSS and CHM format
files. KchmViewer is a CHM viewer that includes its own copy of the
chmlib library.

Affected packages
================
    -------------------------------------------------------------------
     Package             /  Vulnerable  /                   Unaffected
    -------------------------------------------------------------------
  1  app-doc/chmlib          < 0.37.4                        >= 0.37.4
  2  app-doc/kchmviewer        < 1.1                            >= 1.1
    -------------------------------------------------------------------
     2 affected packages on all of their supported architectures.
    -------------------------------------------------------------------

Description
==========
Sven Tantau reported about a buffer overflow vulnerability in chmlib.
The function "_chm_decompress_block()" does not properly perform
boundary checking, resulting in a stack-based buffer overflow.

Impact
=====
By convincing a user to open a specially crafted ITSS or CHM file,
using KchmViewer or a program makes use of chmlib, a remote attacker
could execute arbitrary code with the privileges of the user running
the software.

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

Resolution
=========
All chmlib users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=app-doc/chmlib-0.37.4"

All KchmViewer users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=app-doc/kchmviewer-1.1"

References
=========
  [ 1 ] CVE-2005-3318
        
Availability
===========
This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

  https://security.gentoo.org/glsa/200511-23

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 2005 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/2.0/