Heap-based buffer overflow in NSD - CVE-2026-12244
Published: June 25, 2026
Vulnerability identifier: #VU135154
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-2026-12244
CWE-ID: CWE-122
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 heap-based buffer overflow in SVCB RR handling when processing a crafted AXFR response containing a specially crafted SVCB RR. A remote user can send a crafted zone transfer response to execute arbitrary code.
Exploitation requires NSD to be configured as a secondary for a zone, and the malicious input must come from the configured primary for that zone.
How to mitigate CVE-2026-12244
Install security update from vendor's website.