CVE-2026-97206

HIGH 7.5

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

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-416
Vendor	nlnet labs
Product	unbound
Published	Oct 21, 2026

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CVSS v3 Breakdown

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

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

Affected Versions

NLnet Labs / Unbound

1.22.0 < 1.26.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

nlnetlabs.nl: https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt

Credits

Kunta Chu (Tsinghua University) Jianjun Chen (Tsinghua University)