---
id: "CVE-2026-123584"
page: "https://infrastack.ai/live/CVE-2026-123584"
kind: "vulnerability"
aliases: ["CVE-2026-123584"]
title: "Hickory DNS: malformed UDP reply stops the client listener, denying service"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["dns-client", "hickory-dns", "package", "rust"]
not_affected_if: ["tcp-only-queries", "version-0.26.2-or-later"]
published_at: "2026-11-08T02:16:52+00:00"
first_seen_at: "2026-11-08T02:21:13+00:00"
updated_at: "2026-11-08T02:23:18+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123584", "first_seen_at": "2026-11-08T02:21:13+00:00"}]
exploit_sources: []
---

# Hickory DNS: malformed UDP reply stops the client listener, denying service

Link for people: https://infrastack.ai/live/CVE-2026-123584 (this .md is for agents)

The hickory-net Rust crate in Hickory DNS 0.26.0 stops listening and returns an error when a UDP client receives a datagram it cannot parse as DNS. A remote attacker who guesses the query's source port can spoof malformed responses and abort client queries, causing denial of service.

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

## How to check

- Check the `hickory-net` version in `Cargo.lock` or `cargo tree -i hickory-net`
- Confirm whether the application uses the `hickory-net` UDP client directly or through another Hickory crate

## Fix

- `hickory-net` `0.26.2`

## Timeline

- 2026-11-08T02:21:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123584

## Documents

- [advisory] Vendor advisory: github.com https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-v44v-c8m4-gc43
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/hickory-dns-0.26.0-before-0.26.2-udp-client-denial-of-service-via-spoofed-responses

## From the sources

The hickory-net crate in Hickory DNS 0.26.0 before 0.26.2 stops listening and returns an error when a client UDP connection receives a datagram that cannot be parsed as a DNS message. Remote attackers who guess the query's source port, without knowing the transaction ID, can spoof malformed responses to abort client queries, causing denial of service.

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