Vulnerability details

CVE-2026-97206

NLnet Labs Unbound

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

CVSS 3.1

7.5High

Official 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.

CVSS scores

Score	Version	Source	Vector
7.5High	3.1	CVEProject cvelistV5 (CNA) (NLnet Labs)	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`

Affected products

Vendor	Product	Versions	Source
NLnet Labs	Unbound	1.22.0 ≤ v < 1.26.2	CVEProject cvelistV5 (CNA)

References and advisories

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

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Details

Published: 2026-10-21
Last updated: 2026-10-29
State: Published
Assigner (CNA): NLnet Labs

Exploit prediction (EPSS)

0.33%

Probability of exploitation in 30 days

26.8%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: Yes
Exploitation: None
Technical impact: Partial

Weaknesses (CWE)

CWE-416
Use After Free