---
id: "CVE-2026-123608"
page: "https://infrastack.ai/live/CVE-2026-123608"
kind: "vulnerability"
aliases: ["CVE-2026-123608"]
title: "Hickory DNS library: crafted messages exhaust CPU during name compression"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["dns-server", "hickory-dns", "package", "rust"]
not_affected_if: ["client-only-use", "version-0.26.1-or-later"]
published_at: "2026-11-08T02:16:55+00:00"
first_seen_at: "2026-11-08T02:21:14+00:00"
updated_at: "2026-11-08T02:22:43+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123608", "first_seen_at": "2026-11-08T02:21:14+00:00"}]
exploit_sources: []
---

# Hickory DNS library: crafted messages exhaust CPU during name compression

Link for people: https://infrastack.ai/live/CVE-2026-123608 (this .md is for agents)

hickory-proto, the DNS protocol library in the Hickory DNS project, takes quadratic time when encoding messages that carry many records with many candidate labels. A remote attacker can send such DNS messages to exhaust a server's CPU and cause denial of service.

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

## How to check

- Check the version of `hickory-proto` in your Cargo.lock (`cargo tree -i hickory-proto`)
- Check whether your service uses hickory-proto to encode DNS responses (directly or via hickory-dns or hickory-resolver)

## Fix

- `hickory-proto` `0.26.1` (fixed in releases from 0.3.1 up to, but not including, 0.26.1 are affected)

## Timeline

- 2026-11-08T02:21:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123608

## Documents

- [advisory] Vendor advisory: github.com https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-q2qq-hmj6-3wpp
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/hickory-dns-hickory-proto-0.3.1-before-0.26.1-cpu-exhaustion-via-binencoder-name-compression

## From the sources

Hickory DNS hickory-proto from 0.3.1 before 0.26.1 contains a denial of service vulnerability in BinEncoder that allows remote attackers to exhaust CPU through quadratic-time name compression. Attackers can send malicious DNS messages with many records that add many candidate labels and trigger repeated linear scans during encoding, amplifying CPU exhaustion.

---

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