CVE-2014-8500: A Defect in Delegation Handling Can Be Exploited to Crash BIND
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CVE-2014-8500: A Defect in Delegation Handling Can Be Exploited to Crash BIND

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Article summary

Failure to place limits on delegation chaining can allow an attacker to crash BIND or cause memory exhaustion.

CVE: CVE-2014-8500 

Document version: 2.0

Posting date: 08 December 2014

Program impacted: BIND 9

Versions affected: 9.0.x -> 9.8.x, 9.9.0 -> 9.9.6, 9.10.0 -> 9.10.1

Severity: Critical

Exploitable: Remotely


By making use of maliciously-constructed zones or a rogue server, an attacker can exploit an oversight in the code BIND 9 uses to follow delegations in the Domain Name Service, causing BIND to issue unlimited queries in an attempt to follow the delegation. This can lead to resource exhaustion and denial of service (up to and including termination of the named server process.)


All recursive resolvers are affected. Authoritative servers can be affected if an attacker can control a delegation traversed by the authoritative server in servicing the zone.

CVSS Score: 7.8

CVSS Vector: (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: No workarounds exist.  Vulnerable versions of BIND 9 should be upgraded.

Active exploits: No known active exploits.

Solution: Upgrade to the patched release most closely related to your current version of BIND. Patched builds of currently supported branches of BIND (9.9 and 9.10) can be downloaded via

  • BIND 9 version 9.9.6-P1
  • BIND 9 version 9.10.1-P1

Regarding older versions:

  • BIND 9.6-ESV and BIND 9.8 have been officially designated "end of life" (EOL) and no longer receive support. All organizations running EOL branches should be planning transition to currently supported branches. However, due to the severity of this particular issue, source code diffs which can be applied to BIND 9.8 and BIND 9.6-ESV will be made available on request to

Acknowledgements: ISC would like to thank Florian Maury (ANSSI) for discovering and reporting this vulnerability.

Document Revision History:

1.0 Advance Notification, 20 November 2014
2.0 Public Disclosure, 08 December 2014

Related Documents:

If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit

See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.

Do you still have questions? Questions regarding this advisory should go to security-officer@isc.orgTo report a new issue, please encrypt your message using's PGP key which can be found here: If you are unable to use encrypted email, you may also report new issues at:

Note: ISC patches only currently supported versions. When possible, we indicate EOL versions affected. (For current information on which versions are actively supported, please see 

ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy.

This Knowledgebase article is the complete and official security advisory document.

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