What is CVE-2026-42944?

CVE-2026-42944 is a high-severity vulnerability in Nlnet Labs Unbound, classified under CWE-197. CVSS score: 7.5/10. Published 2026-05-20.

How severe is CVE-2026-42944?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Nlnet Labs Unbound

CVE-2026-42944

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid'…

EPSS: 0.001 (18.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Nlnet Labs Unbound — versions 1.14.0
Nlnetlabs Unbound

Weakness classification (CWE)

CWE-197
CWE-787 — Out-of-bounds Write

References

sep@nlnetlabs.nl (vendor-advisory, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-42944?: CVE-2026-42944 is a high-severity vulnerability in Nlnet Labs Unbound, classified under CWE-197. CVSS score: 7.5/10. Published 2026-05-20.
How severe is CVE-2026-42944?: High severity. CVSS v3 base score is 7.5 out of 10.