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Gentoo Linux Security Advisory                           GLSA 201701-28
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: c-ares: Heap-based buffer overflow
     Date: January 11, 2017
     Bugs: #595536
       ID: 201701-28

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Synopsis
========

A heap-based buffer overflow in c-ares might allow remote attackers to
cause a Denial of Service condition.

Background
==========

c-ares is a C library for asynchronous DNS requests (including name
resolves).

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

    -------------------------------------------------------------------
     Package              /     Vulnerable     /            Unaffected
    -------------------------------------------------------------------
  1  net-dns/c-ares               < 1.12.0                  >= 1.12.0

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

A hostname with an escaped trailing dot (such as "hello\\.") would have
its size calculated incorrectly leading to a single byte written beyond
the end of a buffer on the heap.

Impact
======

A remote attacker, able to provide a specially crafted hostname to an
application using c-ares, could potentially cause a Denial of Service
condition.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All c-ares users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=net-dns/c-ares-1.12.0"

References
==========

[ 1 ] CVE-2016-5180
      https://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-5180

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

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

 https://security.gentoo.org/glsa/201701-28

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 2017 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/2.5