Heap Overflow Vulnerability in NSD DNS Server by NLNet Labs
CVE-2026-12244

8.7HIGH

Key Information:

Vendor

Nlnet Labs

Status
Nsd
Vendor
CVE Published:
25 June 2026

What is CVE-2026-12244?

The NSD (Name Server Daemon) exhibits a vulnerability when configured as a secondary server for a DNS zone. An attacker can exploit this issue by sending an AXFR request containing a specially crafted SVCB Resource Record (RR) with an rdata size exceeding the expected limits. This can result in a heap overflow due to an integer overflow during space allocation. This vulnerability allows remote attackers to potentially execute arbitrary code by manipulating memory allocation, which poses substantial risks to DNS services.

Affected Version(s)

NSD 4.14.0 < 4.14.3

References

https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12244.txt
vendor-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Qifan Zhang from Palo Alto Networks
.