CVE-2026-97206

DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.

Published Oct 21, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Solution

This issue is fixed starting with version 1.26.2

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6581-1 unbound security update
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Nlnetlabs
Nlnetlabs unbound
Vendors & Products Nlnetlabs
Nlnetlabs unbound
Type Values Removed Values Added
Description 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.
Title DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.
Weaknesses CWE-416
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
NLnet Labs
Published
Updated
Oct 29, 2026, 7:08 PM
Reserved
Oct 14, 2026, 9:16 AM
Status
Awaiting Analysis
Published
Oct 21, 2026, 9:17 AM
Modified
Oct 29, 2026, 7:17 PM