CVE-2026-101339

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Buffer Overflow in NLnet Labs NSD Due to Malformed HIP Resource Record

Publication date: 2026-10-14

Last updated on: 2026-10-16

Assigner: NLnet Labs

Description

A HIP resource record that fills the RDATA near or at is limit, and has another dname RDATA field (a HIP Rendezvous server) can overwrite the stack with up to 191 bytes of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

CVSS Scores

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Meta Information

Published

2026-10-14

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-15

EPSS Evaluated

2026-10-18

NVD

CVE-2026-101339

EUVD

EUVD-2026-100984

Affected Vendors & Products

Vendor	Product	Version / Range
NLnet	Labs	NSD 4.10.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-121	A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Attack-Flow Graph

Executive Summary

This vulnerability involves a stack overwrite in the NSD DNS server when processing specially crafted HIP resource records. A HIP record with nearly full RDATA and an additional dname field can overwrite up to 191 bytes of stack memory with attacker-controlled data, potentially leading to arbitrary command execution.

Detection Guidance

Detecting this vulnerability requires checking the NSD version and inspecting zone files for malformed HIP resource records. Use 'nsd --version' to check the installed version. If it is between 4.10.0 and 4.15.2, the system is vulnerable. Inspect zone files for HIP records with nearly filled RDATA fields containing dname subfields.

Impact Analysis

If exploited, this vulnerability could allow an attacker to execute arbitrary commands on the system running NSD, potentially leading to full system compromise. Attackers would need to provide a malicious zone file to NSD, which could come from an operator-controlled system.

Compliance Impact

This vulnerability could potentially lead to unauthorized data access or execution of arbitrary commands, which may violate data protection requirements under GDPR (e.g., unauthorized processing or disclosure of personal data) and HIPAA (e.g., unauthorized access to protected health information). The risk depends on whether the affected NSD service handles regulated data.

Mitigation Strategies

Upgrade NSD to version 4.15.3 or apply the manual patch for 4.15.2. After patching, restart NSD. Avoid feeding untrusted zone files directly into NSD. Validate zone files before processing.

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