Operational Notification: Some releases of BIND are too strict when handling referrals containing non-empty answer sections

Michael McNally mcnally at isc.org
Wed Sep 19 23:04:42 UTC 2018


Posting date:        19 September 2018
Program Impacted:    BIND
Versions affected:   9.12.0 -> 9.12.2-P1. Also releases 9.13.0 ->
                     9.13.3 of the 9.13 development branch

Description:

   An unexpected side-effect introduced into the BIND 9.12 branch
   during code refactoring causes referrals with non-empty answer
   sections to be treated as errors, potentially preventing resolution
   of names when it involves referrals from servers providing such
   responses.

Impact:

   A properly constructed referral should not contain information
   in the answer section but prior to the BIND 9.12 branch named
   would tolerate such replies if they were otherwise comprehensible
   as a referral. Beginning with BIND 9.12.0 such messages were
   treated as errors, causing a situation where names which could
   be resolved by prior branches of BIND were no longer resolvable
   due to the stricter interpretation.

Workarounds: none

   Solution: If you are running a version affected by this bug you
   can prevent it by upgrading to a release containing the fix which
   reverses the change in behavior. The patched version can be
   downloaded from http://www.isc.org/downloads/all.

   +  BIND 9 version 9.12.2-P2

Do you have Questions? Questions regarding this notification should
go to support at isc.org.

Additional information on our Operational Notifications is here:
https://www.isc.org/software/notifications, and Phased Disclosure Process
is here: https://www.isc.org/security-vulnerability-disclosure-policy

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