CVE-2026-19401

NameCVE-2026-19401
DescriptionAny 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
nsd (PTS)bookworm4.6.1-1vulnerable
trixie4.12.0-1vulnerable
forky, sid4.15.2-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
nsdsource(unstable)4.15.1-1

Notes

https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txt

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