CVE-2019-6469: BIND Supported Preview Edition can exit with an assertion failure if ECS is in use
  • Updated on 30 May 2019
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CVE-2019-6469: BIND Supported Preview Edition can exit with an assertion failure if ECS is in use

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CVE: CVE-2019-6469

Document version: 2.0

Posting date: 29 May 2019

Program impacted: BIND

Versions affected: BIND Supported Preview Edition version 9.10.5-S1 -> 9.11.6-S1. ONLY BIND Supported Preview Edition releases are affected.

Severity: Medium

Exploitable: Remotely

Description:

An error in the EDNS Client Subnet (ECS) feature for recursive resolvers can cause BIND to exit with an assertion failure when processing a response that has malformed RRSIGs.

Impact:

An attacker who is able to cause a server to perform a query whose answer will be accompanied by malformed RRSIGs can deliberately cause a server to exit if it is using the recursive ECS feature.

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:

Only servers which have enabled the EDNS Client Subnet (ECS) feature can be affected by this defect; it can be prevented by disabling ECS options in the server's configuration.

Active exploits:

None known.

Solution:

Upgrade to the patched release most closely related to your current version of BIND:

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

  • BIND 9.11.7-S1

Acknowledgements: ISC would like to thank Quad9 for reporting this issue.

Document revision history:

1.0 Early Notification, 15 May 2019
2.0 Public Disclosure, 29 May 2019

Related documents:

See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.

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 in the 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.

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