CVE-2026-97206

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductUnbound

PublishedOct 21, 2026

First seenOct 21, 2026

Weakness typeCWE-416Use after free

How to fix

Update

NLnet Labs Unbound1.26.2 or later

Vendor advisories

nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt

Affected products

Product	Affected versions	Fixed in
NLnet Labs Unbound	1.22.0 ≤ v < 1.26.2	1.26.2

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