ISC Security Advisory: Specially Crafted DNS Data Can Cause a Lockup in named

Michael McNally mcnally at
Tue Oct 9 21:12:56 UTC 2012

CVE-2012-5166: Specially crafted DNS data can cause a lockup in named

A nameserver can be locked up if it can be induced to load a specially
crafted combination of resource records.

CVE: CVE-2012-5166
Document Version:          2.0
Posting date: 9 October 2012
Program Impacted: BIND
Versions affected:
   9.2.x -> 9.6.x, 9.4-ESV->9.4-ESV-R5-P1, 9.6-ESV->9.6-ESV-R7-P3,
   9.7.0->9.7.6-P3, 9.8.0->9.8.3-P3, 9.9.0->9.9.1-P3
Severity: Critical


   If specific combinations of RDATA are loaded into a nameserver,
   either via cache or an authoritative zone, a subsequent query
   for a related record will cause named to lock up.

   Please Note: All versions of BIND 9.2, 9.3, 9.4 and 9.5 are also
   affected, but these branches are beyond their "end of life" (EOL)
   and no longer receive testing or security fixes from ISC. For
   current information on which versions are actively supported,
   please see


   A nameserver that has become locked-up due to the problem reported
   in this advisory will not respond to queries or control commands.
   Normal functionality cannot be restored except by terminating
   and restarting named.

   This vulnerability can be exploited remotely against recursive
   servers by inducing them to query for records provided by an
   authoritative server. It affects authoritative servers if one
   of the combinations of resource records is loaded from file,
   provided via zone transfer, or submitted to a zone via dynamic

CVSS Score:  7.8

CVSS Equation:  (AV:N/AC:L/Au:N/C:N/I:N/A:C)

   For more information on the Common Vulnerability Scoring System
   and to obtain your specific environmental score please visit:


   Setting the option 'minimal-responses' to 'yes' will prevent the lockup.

Active exploits: 

   No known active exploits.


   Upgrade to the patched version or new release most closely related
   to your current version of BIND. The patched versions of BIND
   and new releases can be downloaded from

   BIND 9 version 9.7.7, 9.7.6-P4
   BIND 9 version 9.6-ESV-R8, 9.6-ESV-R7-P4
   BIND 9 version 9.8.4, 9.8.3-P4
   BIND 9 version 9.9.2, 9.9.1-P4


   ISC would like to thank Jake Montgomery of Dyn, Inc.

Document Revision History:

   1.0 - 1 Oct., 2012  Advance Notification to Phase 1
   1.1 - 8 Oct., 2012  Notification to Phase 3
   2.0 - 9 Oct., 2012  Notification to Phase 4 (Public)

Related Documents:

   See our BIND Security Matrix for a complete listing of Security
   Vulnerabilities and versions affected.  If you'd like more
   information on our Forum or product support please visit or

   Do you still have questions?  Questions regarding this advisory
   should go to security-officer at

   Note: ISC patches only currently supported versions. When possible
   we indicate EOL versions affected.

   ISC Security Vulnerability Disclosure Policy:  Details of our
   current security advisory policy and practice can be found here:

   The Knowledge Base article
   is the complete and official security advisory document.  There
   is also a summary article located on our website and linking to

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