CVE-2017-3136: An error handling synthesized records could cause an assertion failure when using DNS64 with "break-dnssec yes;"

Michael McNally mcnally at
Thu Apr 13 00:03:49 UTC 2017

CVE:                 CVE-2017-3136
Document Version:    2.0
Posting date:        12 April 2017
Program Impacted:    BIND
Versions affected:   9.8.0 -> 9.8.8-P1, 9.9.0 -> 9.9.9-P6,
                     9.10.0 -> 9.10.4-P6, 9.10.5b1->9.10.5rc1,
                     9.11.0 -> 9.11.0-P3, 9.11.1b1->9.11.1rc1,
                     9.9.3-S1 -> 9.9.9-S8
Severity:            Medium, but only a risk to systems with
                     specific configurations
Exploitable:         Remotely


   A query with a specific set of characteristics could cause a
   server using DNS64 to encounter an assertion failure and terminate.

   An attacker could deliberately construct a query, enabling
   denial-of-service against a server if it was configured to use
   the DNS64 feature and other preconditions were met.


   Servers are at risk if they are configured to use DNS64 and if
   the option "break-dnssec yes;" is in use.

CVSS Score:          5.9
CVSS Vector:         CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

For more information on the Common Vulnerability Scoring System and
to obtain your specific environmental score please visit:


   Servers which have configurations which require DNS64 and
   "break-dnssec yes;" should upgrade.  Servers which are not using
   these features in conjunction are not at risk from this defect.

Active exploits:

   No known active exploits.


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

   -  BIND 9 version 9.9.9-P8
   -  BIND 9 version 9.10.4-P8
   -  BIND 9 version 9.11.0-P5

   BIND Supported Preview Edition is a special feature preview
   branch of BIND provided to eligible ISC support customers.

   -  BIND 9 version 9.9.9-S10

   New development releases of BIND are also available which contain
   the fix for this vulnerability:

   -  BIND 9 version 9.9.10rc3
   -  BIND 9 version 9.10.5rc3
   -  BIND 9 version 9.11.1rc3


   ISC would like to thank Oleg Gorokhov of Yandex for making us
   aware of this vulnerability.

Document Revision History:

   1.0 Advance Notification 08 March 2017
   1.1 Revised Publication Date; Added pre-releases to Versions Affected
       20 March 2017
   2.0 Public Announcement 12 April 2017

Related Documents:

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

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Security Notifications, please visit

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   indicate EOL versions affected.  (For current information on
   which versions are actively supported, please see

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