CVE-2026-97206

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

CVE-2026-97206 is fixed in unbound on 1 platform, first by DEBIAN-CVE-2026-97206, released October 24, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

7.5

Important

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0033

26th percentile

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.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
unbound · Debian 13.5 (trixie)	1.26.2-0+deb13u1	DEBIAN-CVE-2026-97206	Oct 24, 2026
unbound · Debian 14	1.26.2-1	DEBIAN-CVE-2026-97206	Oct 24, 2026

Details

Published
October 21, 2026
Weakness
Use After Free
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97206

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