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Vulnerability record · CVE-2026-12244 · published 25 June 2026

CVE-2026-12244: Nlnetlabs nsd heap-based buffer overflow vulnerability

Nlnetlabs · Nsd

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

8.7 CVSS 4.0 High EPSS 0.49% · top 60.5% CWE-122 · Heap-based buffer overflowCWE-190 · Integer overflow
8.7CVSS 4.0 base score
0.49%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
26 Jun 2026Last modified by NVD

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

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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12244.txt PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-12244), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.