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HIGH · 7.5

CVE-2026-19401

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 i...

Vulnerability Description

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.

CVSS Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH

Affected Products

VendorProductVersions
NlnetlabsNsd>= 4.3.7, < 4.15.1

Related Weaknesses (CWE)

CWE-617CWE-400

References

FAQ

What is CVE-2026-19401?

CVE-2026-19401 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 i...

How severe is CVE-2026-19401?

CVE-2026-19401 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-19401?

Check the references section above for vendor advisories and patch information. Affected products include: Nlnetlabs Nsd.