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Gentoo Linux Security Advisory                           GLSA 202105-20
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                                            https://security.gentoo.org/
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  Severity: Low
     Title: Dnsmasq: DNS cache poisoning
      Date: May 26, 2021
      Bugs: #782130
        ID: 202105-20

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Synopsis
========

Use of insufficient randomness in Dnsmasq might lead to DNS Cache
Poisoning.

Background
==========

Dnsmasq is a lightweight and easily-configurable DNS forwarder and DHCP
server.

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

     -------------------------------------------------------------------
      Package              /     Vulnerable     /            Unaffected
     -------------------------------------------------------------------
   1  net-dns/dnsmasq               < 2.85                     >= 2.85

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

It was discovered that Dnsmasq, when configured with
--server=<address>@<interface> or similar (e.g. through dbus),
configured a fixed UDP port for all outgoing queries to the specified
upstream DNS server.

Impact
======

An attacker, by sending malicious crafted DNS responses, could perform
a DNS Cache Poisoning attack.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All Dnsmasq users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot --verbose ">=net-dns/dnsmasq-2.85"

References
==========

[ 1 ] CVE-2021-3448
       https://nvd.nist.gov/vuln/detail/CVE-2021-3448

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

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

  https://security.gentoo.org/glsa/202105-20

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 2021 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