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CVE-2012-5166: Specially crafted DNS data can cause a lockup in named
Author: Cathy Almond Reference Number: AA-00801 Views: 42965 Created: 2012-09-26 13:55 Last Updated: 2012-10-17 14:57 0 Rating/ Voters
A nameserver can be locked up if it can be induced to load a specially crafted combination of resource records.

Document Version:        
Posting date: 
9 October 2012
Program Impacted: 
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



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 update.

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.

Solution:  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

Acknowledgement:  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)

2.1 - 17 Oct., 2012 Added Chinese translation.  Added link to FAQ supplemental article in KB.

Related Documents:

A Japanese translation of this document is available at:

A Spanish translation of this document is available at:

A Chinese translation of this document is available at:

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

This new KnowledgeBase article includes additional information and Frequently Asked Questions about this advisory.

Do you still have questions?  Questions regarding this advisory should go to

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:

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

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