---
id: CVE-2026-123570
title: Hickory DNS from 0.18 before 0.26.2 Memory Amplification DoS via RR Counts
summary: >-
  The DNS wire-format message parser in hickory-proto (Hickory DNS) 0.18 before
  0.26.2 preallocates record vectors sized by the untrusted ANCOUNT, NSCOUNT,
  and ARCOUNT header fields before reading record data. Remote attackers can
  send a U…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-400
vendor: hickory-dns
product: hickory-dns
affected:
  - hickory-dns >= 0.18 < 0.26.2
published: '2026-11-08'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T01:38:07.919Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123570'
references:
  - url: >-
      https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-67wc-6jq8-ghrc
    label: GitHub Security Advisory (GHSA-67wc-6jq8-ghrc)
  - url: >-
      https://www.vulncheck.com/advisories/hickory-dns-from-0.18-before-0.26.2-memory-amplification-dos-via-rr-counts
    label: >-
      VulnCheck Advisory: Hickory DNS from 0.18 before 0.26.2 Memory
      Amplification DoS via RR Counts
tags:
  - cve.org
ingestedAt: '2026-11-08T02:43:18.657Z'
---

## Overview

The DNS wire-format message parser in hickory-proto (Hickory DNS) 0.18 before 0.26.2 preallocates record vectors sized by the untrusted ANCOUNT, NSCOUNT, and ARCOUNT header fields before reading record data. Remote attackers can send a UDP datagram, or a spoofed response to a client/resolver, with these counts set to 65535, forcing about 18MB of allocation per message.

## Affected

- `hickory-dns >= 0.18 < 0.26.2`

## Remediation

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