CVE-2026-12244: Nlnetlabs Nsd

High severity, CVSS 8.8. EPSS: 0.5% chance of exploitation in the next 30 days.

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

Affected products

• Nlnetlabs Nsd: from 4.14.0, before 4.14.3 (fixed in 4.14.3)

Published 2026-06-25. Last modified 2026-06-26.