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 allocate space needed for the RR wrap (because total size > 65535), causing a heap overflow. The attacker can perform a controlled (RCE class) head write of up to 65509 bytes
History

Tue, 30 Jun 2026 00:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.0, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H'}

threat_severity

Important


Thu, 25 Jun 2026 13:30:00 +0000

Type Values Removed Values Added
First Time appeared Nlnetlabs
Nlnetlabs nsd
Vendors & Products Nlnetlabs
Nlnetlabs nsd
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 25 Jun 2026 06:45:00 +0000

Type Values Removed Values Added
Description 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 allocate space needed for the RR wrap (because total size > 65535), causing a heap overflow. The attacker can perform a controlled (RCE class) head write of up to 65509 bytes
Title Heap overflow and crash with crafted SVCB RR
Weaknesses CWE-122
CWE-190
References
Metrics cvssV4_0

{'score': 8.7, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published: 2026-06-25T05:24:08.548Z

Updated: 2026-06-25T12:45:34.403Z

Reserved: 2026-06-15T06:46:44.866Z

Link: CVE-2026-12244

cve-icon Vulnrichment

Updated: 2026-06-25T12:45:30.211Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-06-25T00:00:00Z

Links: CVE-2026-12244 - Bugzilla