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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-97206
StatePUBLISHED
AssignerNLnet Labs
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-21 09:17:08 UTC
Updated2026-10-22 15:22:40 UTC
DescriptionNLnet 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.002630000 probability, percentile 0.171060000 (date 2026-10-22)

Problem Types: CWE-416 | CWE-416 CWE-416: Use After Free

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA NLnet Labs Unbound affected 1.22.0 1.26.2 semver Not specified

References

ReferenceSourceLinkTags
www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt [email protected] www.nlnetlabs.nl
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Kunta Chu (Tsinghua University) (en)

CNA: Jianjun Chen (Tsinghua University) (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-09-20T00:00:00.000ZIssue reported by Kunta Chu
CNA2026-09-29T00:00:00.000ZNLnet Labs shares patch
CNA2026-09-30T00:00:00.000ZKunta Chu verifies patch
CNA2026-10-21T00:00:00.000ZFixes released with version 1.26.2

Solutions

CNA: This issue is fixed starting with version 1.26.2

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