---
id: CVE-2026-97206
title: >-
  DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on
  multi-threaded deployments.
summary: >-
  NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a
  DNS-over-QUIC (DoQ) lifetime bug reachable by a remote DoQ client under
  multi-threaded operation. A client-triggered QUIC path migration can enter
  stream/connectio…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-416
vendor: NLnet Labs
product: Unbound
affected:
  - Unbound >= 1.22.0 < 1.26.2
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T08:57:41.106Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-97206'
references:
  - url: 'https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt'
tags:
  - cve.org
ingestedAt: '2026-10-21T09:46:15.395Z'
---

## Overview

NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a DNS-over-QUIC (DoQ) lifetime bug reachable by a remote DoQ client under multi-threaded operation. A client-triggered QUIC path migration can enter stream/connection cleanup while a mesh reply still retains a pointer to the DoQ stream. Cleanup frees the DoQ stream and when the pending mesh reply later completes it dereferences a stale pointer leading to a crash.

## Affected

- `Unbound >= 1.22.0 < 1.26.2`

## Remediation

This issue is fixed starting with version 1.26.2