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Gentoo Linux Security Advisory                           GLSA 200511-23
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                                            http://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
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chmlib and KchmViewer contain a buffer overflow vulnerability which may
lead to the execution of arbitrary code.

Background
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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
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    -------------------------------------------------------------------
     Package             /  Vulnerable  /                   Unaffected
    -------------------------------------------------------------------
  1  app-doc/chmlib          < 0.37.4                        >=3D 0.37.4
  2  app-doc/kchmviewer        < 1.1                            >=3D 1.1
    -------------------------------------------------------------------
     2 affected packages on all of their supported architectures.
    -------------------------------------------------------------------

Description
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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
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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
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There is no known workaround at this time.

Resolution
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All chmlib users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=3Dapp-doc/chmlib-0.37.4"

All KchmViewer users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=3Dapp-doc/kchmviewer-1.1"

References
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  [ 1 ] CVE-2005-3318
        http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2005-331=
8

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

  http://security.gentoo.org/glsa/glsa-200511-23.xml

Concerns?
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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
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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.

http://creativecommons.org/licenses/by-sa/2.0