---
id: "CVE-2026-123578"
page: "https://infrastack.ai/live/CVE-2026-123578"
kind: "vulnerability"
aliases: ["CVE-2026-123578"]
title: "Hickory DNS: UDP responses with empty question section skip spoofing checks"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["dns", "hickory-dns", "package", "rust"]
not_affected_if: ["not-using-hickory", "tcp-only"]
published_at: "2026-11-08T02:16:51+00:00"
first_seen_at: "2026-11-08T02:21:12+00:00"
updated_at: "2026-11-08T02:25:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123578", "first_seen_at": "2026-11-08T02:21:12+00:00"}]
exploit_sources: []
---

# Hickory DNS: UDP responses with empty question section skip spoofing checks

Link for people: https://infrastack.ai/live/CVE-2026-123578 (this .md is for agents)

Hickory DNS libraries skip the check that a UDP DNS response's question matches the query when the question count is zero, and also skip the case-randomization check. An attacker who can inject spoofed UDP responses can use this to weaken defenses against DNS spoofing.

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

## How to check

- Look for the `hickory-net` crate at `0.26.0` up to but not including `0.26.2`, or `hickory-proto` at `0.25.0` through `0.25.2`, in `Cargo.lock` or `cargo tree`.
- Check whether the application uses Hickory DNS as a DNS client or resolver over UDP.

## Fix

- `hickory-net`: move to `0.26.2` or later.
- `hickory-proto`: the sources state the affected range `0.25.0` through `0.25.2`; the fixed version is not stated in the given sources.

## Timeline

- 2026-11-08T02:21:12+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123578

## Documents

- [advisory] Vendor advisory: github.com https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3w89-7rx5-hpwx
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/hickory-dns-0.26.0-before-0.26.2-response-validation-bypass-via-qdcount-0

## From the sources

Hickory DNS hickory-net 0.26.0 before 0.26.2 and hickory-proto 0.25.0 through 0.25.2 skip the check that a UDP response's question section matches the query when the response has an empty question section (QDCOUNT=0), and also skip the case-randomization check. Remote attackers able to inject spoofed UDP responses can send QDCOUNT=0 responses to bypass these checks, weakening defenses against DNS spoofing.

---

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