What is CVE-2026-12246?

CVE-2026-12246 is a high-severity vulnerability in Nlnet Labs Nsd, classified under Improper Input Validation. CVSS score: 8.1/10. Published 2026-06-25.

How severe is CVE-2026-12246?

High severity. CVSS v3 base score is 8.1 out of 10.

Buffer overflow in Nlnet Labs Nsd

CVE-2026-12246

NSD version 4.14.0 introduced a bug where a specially crafted APL RR, with an adflength larger than permitted for the address family will overwrite the stack when the zone is written to disk, with a maximum of 111 attacker controlled bytes.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

EPSS: 0.002 (14.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H.

Affected products

Nlnet Labs Nsd — versions 4.14.0
Nlnetlabs Nsd

Weakness classification (CWE)

CWE-20 — Improper Input Validation
CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

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

Frequently asked questions

What is CVE-2026-12246?: CVE-2026-12246 is a high-severity vulnerability in Nlnet Labs Nsd, classified under Improper Input Validation. CVSS score: 8.1/10. Published 2026-06-25.
How severe is CVE-2026-12246?: High severity. CVSS v3 base score is 8.1 out of 10.