CVE-2026-19401 — Remote UDP DoS by sending multiple DNS Cookie options

CVE-2026-19401

Remote UDP DoS by sending multiple DNS Cookie options PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
NLnet Labs / NSD	affected 4.3.7 before 4.15.1

CWE

CWE-617, CWE-400

References

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

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.