What is CVE-2026-97206?

CVE-2026-97206 is a high-severity vulnerability in Nlnet Labs Unbound, classified under Use After Free. CVSS score: 7.5/10. Published 2026-10-21.

How severe is CVE-2026-97206?

High severity. CVSS v3 base score is 7.5 out of 10.

Use After Free in Nlnet Labs Unbound

CVE-2026-97206

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.

Vulnerability class: Use-After-Free

Published 2026-10-21.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Nlnet Labs Unbound

Weakness classification (CWE)

CWE-416 — Use After Free

References

www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt (vendor-advisory)

Frequently asked questions

What is CVE-2026-97206?: CVE-2026-97206 is a high-severity vulnerability in Nlnet Labs Unbound, classified under Use After Free. CVSS score: 7.5/10. Published 2026-10-21.
How severe is CVE-2026-97206?: High severity. CVSS v3 base score is 7.5 out of 10.