---
title: "CVE-2026-80274: Validating resolver can abort while caching a mismatched NOQNAME proof"
slug: "cve-2026-80274"
description: "A BIND DNSSEC resolver query with a valid wildcard answer and signed NSEC3 proof, followed by an unsigned NSEC at the same owner name, may trigger named to exit"
status: "new"
updated: 2026-09-16T12:40:30Z
published: 2026-09-16T12:40:30Z
canonical: "kb.isc.org/cve-2026-80274"
---

> ## 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-2026-80274: Validating resolver can abort while caching a mismatched NOQNAME proof

**CVE:** [CVE-2026-80274](https://www.cve.org/CVERecord?id=CVE-2026-80274)

**Title:** Validating resolver can abort while caching a mismatched NOQNAME proof

**Document version:** 2.0

**Posting date:** 16 September 2026

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

**Versions affected:**

BIND

- 9.11.0 -> 9.18.50
- 9.20.0 -> 9.20.27
- 9.21.0 -> 9.21.25

BIND Supported Preview Edition

- 9.11.3-S1 -> 9.18.50-S1
- 9.20.9-S1 -> 9.20.27-S1

**Severity:** High

**Exploitable:** Remotely

**Description:**

If a BIND resolver sends a query for a DNSSEC-signed authoritative zone, and the authoritative server replies with a valid wildcard answer and signed NSEC3 proof, followed by an unsigned NSEC at the same owner name, it will trigger an unexpected program exit.

**Impact:**

A successful attack could cause an unexpected program exit and denial-of-service.

**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:**

No workarounds known.

**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:

- 9.20.29
- 9.21.26

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

- 9.20.29-S1

**Acknowledgments:**

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

**Document revision history:**

- 1.0 Early Notification, 9 September 2026
- 1.1 Revised the list of fixed versions, 11 September 2026
- 2.0 Public disclosure, 16 September 2026

**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 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-2026-80274](https://kb.isc.org/docs/cve-2026-80274) 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.