Operational Notification: Some releases of BIND 9.12 are too strict when handling referrals

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 https://www.isc.org/downloads/.

• BIND 9 version 9.12.2-P2

Do you still have questions? Questions regarding this advisory should go to security-officer@isc.org. To report a new issue, please encrypt your message using security-officer@isc.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/.

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 https://www.isc.org/downloads/). 

ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: ISC Software Defect and Security Vulnerability Disclosure Policy.

This Knowledgebase article is the complete and official security advisory document.

Legal Disclaimer:

Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time. A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors.