Stack-based buffer overflow in NSD - CVE-2026-12246
Published: June 25, 2026
Vulnerability identifier: #VU135156
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-12246
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: NLnet Labs
Affected software:
NSD
NSD
Detailed vulnerability description
The vulnerability allows a remote user to execute arbitrary code.
The vulnerability exists due to a stack-based buffer overflow in the APL RR rdata handling logic when writing a zonefile to disk. A remote user can provide a specially crafted APL resource record with an oversized adflength value to execute arbitrary code.
Exploitation requires control of data from a configured primary in a multi-tenant secondary DNS deployment.
How to mitigate CVE-2026-12246
Install security update from vendor's website.