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CVE-2015-8461: A race condition when handling socket errors can lead to an assertion failure in resolver.c
Author: Michael McNally Reference Number: AA-01319 Views: 55764 Created: 2015-12-15 16:30 Last Updated: 2016-04-18 23:32 0 Rating/ Voters

Document Version:          
Posting date: 
15 December 2015
Program Impacted: 
Versions affected: 
9.9.8 -> 9.9.8-P1, 9.9.8-S1 -> 9.9.8-S2, 9.10.3 -> 9.10.3-P1


Beginning with the September 2015 maintenance releases 9.9.8 and 9.10.3, an error was introduced into BIND 9 which can cause a server to exit after encountering an INSIST assertion failure in resolver.c


An uncommonly occurring condition can cause affected servers to exit with an INSIST failure depending on the outcome of a race condition in resolver.c  While difficult to exploit reliably, a malicious party could, through deliberate behavior, significantly increase the probability of encountering the triggering condition, resulting in denial-of-service to clients if successful.

CVSS Score:  5.4

CVSS Vector:  (AV:N/AC:H/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:



Active exploits:

None known.

Solution:  Upgrade to the patched release most closely related to your current version of BIND. Public open-source branches can be downloaded from

  • BIND 9 version 9.9.8-P2
  • BIND 9 version 9.10.3-P2

BIND 9 Supported Preview edition is a feature preview version of BIND provided exclusively to eligible ISC Support customers.

  • BIND 9 version 9.9.8-S3

Acknowledgements: ISC would like to thank John O'Brien of the University of Pennsylvania for discovering this issue.

Document Revision History:

1.0 Advance Notification 8 December 2015
2.0 Public Disclosure, 15 December 2015

Related Documents:

See our BIND9 Security Vulnerability Matrix at for a complete listing of Security Vulnerabilities and versions affected.

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This Knowledge Base article is the complete and official security advisory document.

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