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

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
NLnet Labs NSD unaffected
Version Status Constraints
4.14.0 affected < 4.14.3

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Project Subscriptions

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Advisories

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Fixes

Solution

This issue is fixed starting with version 4.14.3.

Workaround

No workaround given by the vendor.

References
Link Providers
https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12244.txt cve-icon
History

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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published:

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

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

Link: CVE-2026-12244

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-06-25T07:30:17Z

Weaknesses