--- title: "CVE-2023-5679" slug: "cve-2023-5679" 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." status: "new" updated: 2024-02-13T13:22:39Z published: 2024-02-13T13:22:39Z --- > ## Documentation Index > Fetch the complete documentation index at: https://kb.isc.org/llms.txt > Use this file to discover all available pages before exploring further. # CVE-2023-5679: Enabling both DNS64 and serve-stale may cause an assertion failure during recursive resolution **CVE:** [CVE-2023-5679](https://cve.mitre.org/cgi-bin/cvename.cgi?name=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](https://www.isc.org/bind/) **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](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](https://kb.isc.org/docs/aa-00913) 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](mailto:bind-security@isc.org) or posted as confidential GitLab issues at [https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue[confidential]=true](https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue%5Bconfidential%5D=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/](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](https://kb.isc.org/docs/aa-00861). The Knowledgebase article [https://kb.isc.org/docs/cve-2023-5679](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.