Cyber Resilience

CVE-2026-12244

High

Published: 25 June 2026

Published
25 June 2026
Modified
26 June 2026
KEV Added
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Patch
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CVSS Score v4 8.7 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:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0030 22.0th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-12244 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Nlnetlabs Nsd. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 22.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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)…

more

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

CWE(s)
CWE-122CWE-190

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Remote heap overflow in NSD DNS server (secondary) triggered via malicious AXFR from primary enables RCE on public-facing DNS service.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

nlnetlabs
nsd
4.14.0 — 4.14.3

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References