---
id: CVE-2026-123596
title: >-
  Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via
  Ancestor-Delegation NSEC
summary: >-
  Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1
  before 0.26.2 contain a DNSSEC validation flaw in the validating recursor's
  NSEC handler that accepts parent-side ancestor-delegation NSEC records as
  proof of…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-345
vendor: hickory-dns
product: hickory-dns
affected:
  - hickory-dns <= 0.26.0-alpha.1
  - hickory-dns >= 0.26.0-beta.1 < 0.26.2
published: '2026-11-08'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T01:38:25.747Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123596'
references:
  - url: >-
      https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3r6v-f3jh-vvqm
    label: GitHub Security Advisory (GHSA-3r6v-f3jh-vvqm)
  - url: >-
      https://www.vulncheck.com/advisories/hickory-dns-through-0.26.0-alpha.1-dnssec-validation-bypass-via-ancestor-delegation-nsec
    label: >-
      VulnCheck Advisory: Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation
      Bypass via Ancestor-Delegation NSEC
tags:
  - cve.org
ingestedAt: '2026-11-08T02:43:18.649Z'
---

## Overview

Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 contain a DNSSEC validation flaw in the validating recursor's NSEC handler that accepts parent-side ancestor-delegation NSEC records as proof of nonexistence for names below the zone cut. An on-path attacker, rogue parent nameserver, or attacker winning a port and TXID race can deliver one forged NXDOMAIN response built from genuinely signed parent NSEC records, causing authenticated denial of existing child-zone names cached for the negative TTL.

## Affected

- `hickory-dns <= 0.26.0-alpha.1`
- `hickory-dns >= 0.26.0-beta.1 < 0.26.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.