CVE-2026-101341

Deferred Deferred - Pending Action

Buffer Overflow in NSD DNS Server Due to Improper Rdata Validation

Publication date: 2026-10-14

Last updated on: 2026-10-16

Assigner: NLnet Labs

Description

Tokens of text in RDATA (of for example TXT records) under 32 bytes are not checked to stay within the space reserved for the RDATA allowing for arbitrary sized out of bound stack writes, including an overwrite of a callback function pointer which is called directly after parse. Zone files which are written out by NSD itself, such 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-2026-101341

EUVD

EUVD-2026-100985

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

CVE-2026-101341 is a vulnerability in the NSD DNS server software where tokens in RDATA (like TXT records) under 32 bytes are not properly checked. This allows out-of-bounds stack writes, including overwriting a callback function pointer that is called after parsing. Exploiting this requires a specially crafted zone file fed directly into NSD.

Detection Guidance

Check NSD version with 'nsd -v'. If running versions 4.10.0 through 4.15.2, the system is potentially vulnerable. Monitor DNS traffic for malformed TXT or similar records under 32 bytes in RDATA. Inspect zone files for unexpected content before loading into NSD.

Impact Analysis

This vulnerability could allow an attacker to execute arbitrary commands on the system running NSD. Since it involves overwriting a callback function pointer, it may lead to remote code execution. The impact depends on the privileges of the NSD process and the system configuration.

Compliance Impact

This vulnerability allows arbitrary command execution due to out-of-bounds stack writes in NSD's DNS server software. For organizations handling sensitive data under GDPR or HIPAA, this could lead to unauthorized access, data breaches, or loss of integrity of personal health or personally identifiable information. Exploitation requires a malicious zone file, potentially compromising compliance with data protection requirements.

Mitigation Strategies

Upgrade NSD to version 4.15.3 or later. If upgrading is not possible, apply the manual patch to NSD 4.15.2. Avoid loading zone files from untrusted sources. Validate all zone files before processing with NSD.

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