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ESB-2016.0651 - [Win][UNIX/Linux] BIND: Denial of service - Remote/unauthenticated

Date: 10 March 2016

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             AUSCERT External Security Bulletin Redistribution

 CVE-2016-2088: A response containing multiple DNS cookies causes servers
      with cookie support enabled to exit with an assertion failure.
                               10 March 2016


        AusCERT Security Bulletin Summary

Product:           BIND
Publisher:         ISC
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2016-2088  

Original Bulletin:

- --------------------------BEGIN INCLUDED TEXT--------------------

CVE-2016-2088: A response containing multiple DNS cookies causes servers with
cookie support enabled to exit with an assertion failure.

Author: Michael McNally 

Reference Number: AA-01351 

Views: 2475 

Created: 2016-03-09 18:30 

Last Updated: 2016-03-09 19:49 

CVE: CVE-2016-2088

Document Version: 2.0

Posting date: 09 March 2016

Program Impacted: BIND

Versions affected: 9.10.0 -> 9.10.3-P3

Severity: High

Exploitable: Remotely


BIND 9.10 has preliminary support for DNS cookies (or source identity tokens),
a proposed mechanism designed to allow lightweight transaction security 
between a querying party and a nameserver. An error in the BIND code 
implementing support for this optional feature permits a deliberately 
misconstructed packet containing multiple cookie options to cause named to 
terminate with an INSIST assertion failure in resolver.c if DNS cookie support
is enabled in the server. Only servers with DNS cookie support enabled at 
build time can be affected by this defect; in servers which do not have DNS 
cookie support selected any cookies encountered will be ignored as unknown 
option types.


Servers which are built with DNS cookie support enabled are vulnerable to 
denial of service if an attacker can cause them to receive and process a 
response that contains multiple cookie options.

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:


Servers which do not have cookie support included are not at risk from this 

When BIND 9.10 is built from ISC-supported source, cookie support is not 
selected by default. In order to be included it must be elected using the 
"--enable-sit" command-line argument when running the "configure" script in 
the top level source directory. Operators with affected servers can 
re-configure and re-build BIND without cookie support if they prefer not to 
upgrade to a release containing the fix. However, ISC-provided binary packages
for Windows do have "--enable-sit" selected. Server operators using the 
Windows binary packages should upgrade to the corrected version.

Active exploits:

No known active exploits.

Solution: Re-configure and re-build BIND without enabling cookie support or 
upgrade to the patched release most closely related to your current version of

BIND 9 version 9.10.3-P4

Document Revision History:

1.0 Advance Notification 02 March 2016

2.0 Public Disclosure. 09 March 2016

Related Documents:

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

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

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using's PGP key which can be found here: If you are
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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

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advisory policy and practice can be found here:

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

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- --------------------------END INCLUDED TEXT--------------------

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