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Gentoo Linux Security Advisory                           GLSA 200603-07
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: flex: Potential insecure code generation
      Date: March 10, 2006
      Bugs: #122940
        ID: 200603-07

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Synopsis
========

flex might generate code with a buffer overflow, making applications
using such scanners vulnerable to the execution of arbitrary code.

Background
==========

flex is a programming tool used to generate scanners (programs which
recognize lexical patterns in text).

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

    -------------------------------------------------------------------
     Package         /   Vulnerable   /                     Unaffected
    -------------------------------------------------------------------
  1  sys-devel/flex      < 2.5.33-r1                      >= 2.5.33-r1

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

Chris Moore discovered a buffer overflow in a special class of
lexicographical scanners generated by flex. Only scanners generated by
grammars which use either REJECT, or rules with a "variable trailing
context" might be at risk.

Impact
======

An attacker could feed malicious input to an application making use of
an affected scanner and trigger the buffer overflow, potentially
resulting in the execution of arbitrary code.

Workaround
==========

Avoid using vulnerable grammar in your flex scanners.

Resolution
==========

All flex users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=sys-devel/flex-2.5.33-r1"

References
==========

  [ 1 ] CVE-2006-0459
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0459

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

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

  http://security.gentoo.org/glsa/glsa-200603-07.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 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/2.0