CVE-2026-123594
Received Received - Intake

NSEC Validation Flaw in Hickory DNS

Publication date: 2026-11-08

Last updated on: 2026-11-08

Assigner: VulnCheck

Description
Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 contain an NSEC validation flaw that returns a secure proof for NXDOMAIN responses when the covering NSEC's Next Domain Name is a strict descendant of the query name, which actually proves the name exists as an empty non-terminal. On-path attackers can flip the unsigned rcode of a genuine signed NODATA response from NOERROR to NXDOMAIN, causing validators to accept forged nonexistence of the name.

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Meta Information

Published
2026-11-08
Last Modified
2026-11-08
Generated
2026-11-08
AI Q&A
2026-11-08
EPSS Evaluated
N/A
NVD
CVE-2026-123594
EUVD
EUVD-2026-119353

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
hickory hickory-proto to 0.26.0 (inc)
hickory hickory-net to 0.26.2 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-345 The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

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Executive Summary

Hickory DNS versions hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 have an NSEC validation flaw. This flaw incorrectly returns a secure proof for NXDOMAIN responses when the covering NSEC's Next Domain Name is a strict descendant of the query name, which actually indicates the name exists as an empty non-terminal. Attackers can exploit this to change the unsigned response code of a genuine signed NODATA response from NOERROR to NXDOMAIN, leading validators to accept a forged nonexistence of the name.

Impact Analysis

This vulnerability allows on-path attackers to manipulate DNS responses, causing systems to incorrectly treat existing domain names as nonexistent. This can disrupt services relying on DNS resolution, lead to failed connections, or enable further attacks by tricking users or systems into interacting with malicious endpoints.

Mitigation Strategies

Update hickory-proto to version 0.26.0-alpha.2 or later and hickory-net to version 0.26.2 or later to address the NSEC validation flaw.

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