What is CVE-2026-12244?

CVE-2026-12244 is a high-severity vulnerability in Nlnet Labs Nsd, classified under Heap-based Buffer Overflow. CVSS score: 8.8/10. Published 2026-06-25.

How severe is CVE-2026-12244?

High severity. CVSS v3 base score is 8.8 out of 10.

Buffer overflow in Nlnet Labs Nsd

CVE-2026-12244

If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR containing a DNS message with a special crafted SVCB RR with an rdata size of 65512, that let's an (uint16_t) variable that is used to alloca…

Vulnerability class: Buffer Overflow

EPSS: 0.003 (17.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

Nlnet Labs Nsd — versions 4.14.0
Nlnetlabs Nsd

Weakness classification (CWE)

CWE-122 — Heap-based Buffer Overflow
CWE-190 — Integer Overflow or Wraparound

References

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

Frequently asked questions

What is CVE-2026-12244?: CVE-2026-12244 is a high-severity vulnerability in Nlnet Labs Nsd, classified under Heap-based Buffer Overflow. CVSS score: 8.8/10. Published 2026-06-25.
How severe is CVE-2026-12244?: High severity. CVSS v3 base score is 8.8 out of 10.