CVE-2026-19401

EUVD-2026-66349
Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 18.94%
Affected Products (NVD)
VendorProductVersion
nlnetlabsnsd
4.3.7 ≤
𝑥
< 4.15.1
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
nsd
bookworm
vulnerable
forky
4.15.2-1
fixed
sid
4.15.2-1
fixed
trixie
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
nsd
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
xenial
needs-triage
Common Weakness Enumeration
References
https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txt