---
title: "CVE-2024-4076: Assertion failure when serving both stale cache data and authoritative zone content"
slug: "cve-2024-4076"
description: "Client queries that trigger serving stale data and that also require lookups in local authoritative zone data may result in an assertion failure."
updated: 2024-07-23T13:04:15Z
published: 2024-07-23T13:04:15Z
canonical: "kb.isc.org/cve-2024-4076"
---

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# CVE-2024-4076: Assertion failure when serving both stale cache data and authoritative zone content

**CVE:** [CVE-2024-4076](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-4076)

**Title:** Assertion failure when serving both stale cache data and authoritative zone content

**Document version:** 2.0

**Posting date:** 23 July 2024

**Program impacted:** [BIND 9](https://www.isc.org/bind/)

**Versions affected:**

BIND

- 9.16.13 -> 9.16.50
- 9.18.0 -> 9.18.27
- 9.19.0 -> 9.19.24

BIND Supported Preview Edition

- 9.11.33-S1 -> 9.11.37-S1
- 9.16.13-S1 -> 9.16.50-S1
- 9.18.11-S1 -> 9.18.27-S1

**Severity:** High

**Exploitable:** Remotely

**Description:**

Client queries that trigger serving stale data and that also require lookups in local authoritative zone data may result in an assertion failure.

**Impact:**

A `named` instance vulnerable to this logic error may terminate unexpectedly.

**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 answers mitigates this issue.

**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:

- 9.18.28
- 9.20.0

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

- 9.18.28-S1

**Acknowledgments:**

ISC would like to thank Daniel Stränger for bringing this vulnerability to our attention.

**Document revision history:**

- 1.0 Early Notification, 10 July 2024
- 1.1 Revised public disclosure date, 16 July 2024
- 2.0 Public disclosure, 23 July 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-2024-4076](https://kb.isc.org/docs/cve-2024-4076) 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.