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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>6. PowerDNS Security Advisory 2006-02: Zero second CNAME TTLs can make PowerDNS exhaust allocated stack space, and crash</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="powerdns.html" title="Chapter 1. The PowerDNS dynamic nameserver" /><link rel="prev" href="powerdns-advisory-2006-01.html" title="5. PowerDNS Security Advisory 2006-01: Malformed TCP queries can lead to a buffer overflow which might be exploitable" /><link rel="next" href="powerdns-advisory-2008-01.html" title="7. PowerDNS Security Advisory 2008-01: System random generator can be predicted, leading to the potential to 'spoof' PowerDNS Recursor" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6. PowerDNS Security Advisory 2006-02: Zero second CNAME TTLs can make PowerDNS exhaust allocated stack space, and crash</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="powerdns-advisory-2006-01.html">Prev</a> </td><th width="60%" align="center">Chapter 1. The PowerDNS dynamic nameserver</th><td width="20%" align="right"> <a accesskey="n" href="powerdns-advisory-2008-01.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="6. PowerDNS Security Advisory 2006-02: Zero second CNAME TTLs can make PowerDNS exhaust allocated stack space, and crash"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="powerdns-advisory-2006-02"></a>6. PowerDNS Security Advisory 2006-02: Zero second CNAME TTLs can make PowerDNS exhaust allocated stack space, and crash</h2></div></div></div><p>
</p><div class="table"><a id="idp7609088"></a><p class="title"><b>Table 1.2. PowerDNS Security Advisory</b></p><div class="table-contents"><table summary="PowerDNS Security Advisory" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td>
CVE
</td><td>
CVE-2006-4252
</td></tr><tr><td>
Date
</td><td>
13th of November 2006
</td></tr><tr><td>
Affects
</td><td>
PowerDNS Recursor versions 3.1.3 and earlier, on all operating systems.
</td></tr><tr><td>
Not affected
</td><td>
No versions of the PowerDNS Authoritative Server ('pdns_server') are affected.
</td></tr><tr><td>
Severity
</td><td>
Moderate
</td></tr><tr><td>
Impact
</td><td>
Denial of service
</td></tr><tr><td>
Exploit
</td><td>
This problem can be triggered by sending queries for specifically configured domains
</td></tr><tr><td>
Solution
</td><td>
Upgrade to PowerDNS Recursor 3.1.4, or apply <a class="ulink" href="http://wiki.powerdns.com/projects/trac/changeset/919" target="_top">commit 919</a>.
</td></tr><tr><td>
Workaround
</td><td>
None known. Exposure can be limited by configuring the <span class="command"><strong>allow-from</strong></span> setting so only trusted users
can query your nameserver.
</td></tr></tbody></table></div></div><p><br class="table-break" />
</p><p>
PowerDNS would recurse endlessly on encountering a CNAME loop consisting entirely of zero second CNAME records, eventually exceeding resources and crashing.
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