---
id: "CVE-2026-123570"
page: "https://infrastack.ai/live/CVE-2026-123570"
kind: "vulnerability"
aliases: ["CVE-2026-123570"]
title: "Hickory DNS: crafted DNS message forces 18MB allocation per packet"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cargo", "dns", "hickory-dns", "package", "rust"]
not_affected_if: ["not-using-hickory-proto", "version-0.26.2-or-later"]
published_at: "2026-11-08T02:16:49+00:00"
first_seen_at: "2026-11-08T02:21:12+00:00"
updated_at: "2026-11-08T02:23:00+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123570", "first_seen_at": "2026-11-08T02:21:12+00:00"}]
exploit_sources: []
---

# Hickory DNS: crafted DNS message forces 18MB allocation per packet

Link for people: https://infrastack.ai/live/CVE-2026-123570 (this .md is for agents)

The DNS message parser in hickory-proto preallocates memory based on untrusted record counts in the packet header before reading the records. A remote attacker can send a UDP datagram, or a spoofed response to a resolver, with the counts set to 65535 to force about 18MB of allocation per message.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the hickory-proto version in your Cargo.lock or dependency tree, for example `cargo tree -i hickory-proto`
- Check whether your service uses hickory-proto or hickory-resolver/hickory-server as a DNS parser or resolver

## Fix

- hickory-proto: move to `0.26.2` or later (fixed version per the description; the product ranges were not supplied)

## Timeline

- 2026-11-08T02:21:12+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123570

## Documents

- [advisory] Vendor advisory: github.com https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-67wc-6jq8-ghrc
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/hickory-dns-from-0.18-before-0.26.2-memory-amplification-dos-via-rr-counts

## From the sources

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.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_