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

[Michael McNally]

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,
9.9.10b1->9.9.10rc1,
                     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

Description:

   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.

Impact:

   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:
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Workarounds:

   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.

Solution:

   Upgrade to the patched release most closely related to your
   current version of BIND. These can all be downloaded from
   http://www.isc.org/downloads.

   -  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

Acknowledgements:

   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
   https://kb.isc.org/article/AA-00913 for a complete listing of
   Security Vulnerabilities and versions affected.

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Security Notifications, please visit http://www.isc.org/support/.

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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
   http://www.isc.org/downloads/).

ISC Security Vulnerability Disclosure Policy:
   Details of our current security advisory policy and practice can
   be found here: https://kb.isc.org/article/AA-00861

This Knowledge Base article https://kb.isc.org/article/AA-01465 is
the complete and official security advisory document.

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