High severity · published Oct 21, 2026
CVE-2026-97206
DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.
7.5
CVSS
0.3%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UN
Unbound · NLnet Labs
1.22.0 before 1.26.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-97206
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-97206
www.nlnetlabs.nl
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt
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