Vulnerability Note VU#697164

BIND vulnerable to an INSIST failure via sending of multiple recursive queries

Original Release date: 05 Sep 2006 | Last revised: 02 Oct 2006


A vulnerability in the BIND name server could allow a remote attacker to cause a denial of service against an affected system.


The Berkeley Internet Name Domain (BIND) is a popular Domain Name System (DNS) implementation from Internet Systems Consortium (ISC). A flaw exists in the way that some versions of BIND handle recursive queries. It is possible for a remote attacker to trigger an INSIST failure by sending enough recursive queries that the response to the query arrives after all the clients looking for the response have left the recursion queue.

This vulnerability affects BIND 9.3.x versions 9.3.0, 9.3.1, 9.3.2, 9.3.3b, and 9.3.3rc1, and BIND 9.4.x versions 9.4.0a1, 9.4.0a2, 9.4.0a3, 9.4.0a4, 9.4.0a5, 9.4.0a6, and 9.4.0b1.

Note that although BIND versions 9.2.x also contain the underlying flaw that causes this vulnerability, ISC reports that the vulnerability is not exposed by these versions. Nonetheless, ISC has provided a patch for these versions as well.


A remote attacker may be able to cause the name server daemon to crash, thereby causing a denial of service for DNS operations.


Apply a patch from the vendor

Patches have been released in response to this issue. Please see the Systems Affected section of this document.


Users who compile their own versions of BIND from the original ISC source code are encouraged to upgrade to BIND 9.2.6-P1 or BIND 9.3.2-P1 as appropriate. Patches for this issue are also included in BIND versions 9.2.7rc2, 9.3.3rc2, and 9.4.0b2. Patched versions of the software are available from the BIND download page.

Restrict Access

Administrators, particularly those who are unable to apply a patch, can limit exposure to this vulnerability by restricting sources that can ask for recursion.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Debian GNU/LinuxAffected23 Aug 200611 Sep 2006
F5 Networks, Inc.Affected23 Aug 200607 Sep 2006
FreeBSD, Inc.Affected23 Aug 200607 Sep 2006
Gentoo LinuxAffected23 Aug 200602 Oct 2006
Internet Software ConsortiumAffected03 Jul 200606 Sep 2006
Mandriva, Inc.Affected23 Aug 200611 Sep 2006
NetBSDAffected23 Aug 200602 Oct 2006
OpenBSDAffected23 Aug 200607 Sep 2006
OpenPKGAffected-07 Sep 2006
Openwall GNU/*/LinuxAffected23 Aug 200611 Sep 2006
rPathAffected-25 Sep 2006
Slackware Linux Inc.Affected23 Aug 200602 Oct 2006
Trustix Secure LinuxAffected23 Aug 200602 Oct 2006
UbuntuAffected23 Aug 200607 Sep 2006
HitachiNot Affected23 Aug 200605 Sep 2006
If you are a vendor and your product is affected, let us know.View More »

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



Thanks to Joao Damas of the Internet Software Consortium for reporting this vulnerability.

This document was written by Chad R Dougherty.

Other Information

  • CVE IDs: CVE-2006-4096
  • Date Public: 05 Sep 2006
  • Date First Published: 05 Sep 2006
  • Date Last Updated: 02 Oct 2006
  • Severity Metric: 5.67
  • Document Revision: 13


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