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CVE-2012-3817: Heavy DNSSEC Validation Load Can Cause a "Bad Cache" Assertion Failure in BIND9
Author: Michael McNally Reference Number: AA-00729 Views: 29650 Created: 2012-07-20 16:59 Last Updated: 2014-12-12 15:46 0 Rating/ Voters

Title: Heavy DNSSEC Validation Load Can Cause a "Bad Cache" Assertion Failure in BIND9

Summary: High numbers of queries with DNSSEC validation enabled can cause an assertion failure in named, caused by using a "bad cache" data structure before it has been initialized.

CVE: CVE-2012-3817

Document Version: 2.3

Posting date: 24 July, 2012

Program Impacted: BIND 9

Versions affected:

9.6-ESV through 9.6-ESV-R7-P1; 9.7.1 through 9.7.6-P1; 9.8.0 through 9.8.3-P1; 9.9.0 through 9.9.1-P1.

Severity: Critical

Exploitable: Remotely


BIND 9 stores a cache of query names that are known to be failing due to misconfigured name servers or a broken chain of trust. Under high query loads when DNSSEC validation is active, it is possible for a condition to arise in which data from this cache of failing queries could be used before it was fully initialized, triggering an assertion failure.

This bug cannot be encountered unless your server is doing DNSSEC validation.

Please Note: Versions of BIND 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

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:

Workarounds: None

Solution: Upgrade to the patched release most closely related to your current version of BIND. These can all be downloaded from

  • BIND 9 version 9.9.1-P2
  • BIND 9 version 9.8.3-P2
  • BIND 9 version 9.7.6-P2
  • BIND 9 version 9.6-ESV-R7-P2

Exploit Status: None known at this time

Acknowledgment: ISC would like to thank Einar Lonn of

Document Revision History:

1.0 - 11 July, 2012 Phase 1 notice sent
1.1 - 17 July, 2012 Phase 1 re-issued due to change in patch for CVE-2012-3868 that affects 9.9.x only
1.2 - 23 July, 2012 Phase 2 & 3 sent
2.0 - 24 July, 2012 Phase 3 (Public) notified
2.1 - 30 July, 2012 Added Chinese translation
2.2 - 6 August, 2012 Added link to article with additional information/FAQs
2.3 - 12 December 2014 Versions Affected now includes 9.6-ESV (previously 9.6-ESV-R1 through 9.6-ESV-R7-P1)


- Do you have Questions? Questions regarding this advisory should go to

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

- Japanese Translation:

- Spanish Translation

- German Translation:

- Chinese Translation:

This security advisory is also located in our KnowledgeBase:

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

See our BIND Security Matrix for a complete listing of Security Vulnerabilites and versions affected.

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

If you'd like more information on our Forum or BIND/DHCP support please visit or

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