CVE-2023-5679: Enabling both DNS64 and serve-stale may cause an assertion failure during recursive resolution
  • 13 Feb 2024
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CVE-2023-5679: Enabling both DNS64 and serve-stale may cause an assertion failure during recursive resolution

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Article summary

CVE: CVE-2023-5679

Title: Enabling both DNS64 and serve-stale may cause an assertion failure during recursive resolution

Document version: 2.0

Posting date: 13 February 2024

Program impacted: BIND 9

Versions affected:

BIND

  • 9.16.12 -> 9.16.45
  • 9.18.0 -> 9.18.21
  • 9.19.0 -> 9.19.19

BIND Supported Preview Edition

  • 9.16.12-S1 -> 9.16.45-S1
  • 9.18.11-S1 -> 9.18.21-S1

Severity: High

Exploitable: Remotely

Description:

A bad interaction between DNS64 and serve-stale may cause named to crash with an assertion failure during recursive resolution, when both of these features are enabled.

Impact:

By querying a DNS64-enabled resolver for domain names triggering serve-stale, an attacker can cause named to crash with an assertion failure.

CVSS Score: 7.5

CVSS Vector: CVSS:3.1/AV:N/AC:L/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://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1.

Workarounds:

Disabling serve-stale (with stale-cache-enable no; and stale-answer-enable no;) and/or disabling dns64 makes the faulty code path impossible to reach, preventing this flaw from being exploitable.

Active exploits:

We are not aware of any active exploits.

Solution:

Upgrade to the patched release most closely related to your current version of BIND 9:

  • 9.16.48
  • 9.18.24
  • 9.19.21

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

  • 9.16.48-S1
  • 9.18.24-S1

Document revision history:

  • 1.0 Early Notification, 10 January 2024
  • 1.1 Revised Early Notification, 15 January 2024
  • 1.2 Revised the list of fixed versions, 11 February 2024
  • 2.0 Public disclosure, 13 February 2024

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 be mailed to bind-security@isc.org or posted as confidential GitLab issues at https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue[confidential]=true.

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/download/.

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 at https://kb.isc.org/docs/aa-00861.

The Knowledgebase article https://kb.isc.org/docs/cve-2023-5679 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.