---
id: "CVE-2026-123597"
page: "https://infrastack.ai/live/CVE-2026-123597"
kind: "vulnerability"
aliases: ["CVE-2026-123597"]
title: "Hickory DNS: transient DS lookup errors cached, causing zone-wide SERVFAIL"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["dns-resolver", "dnssec", "hickory-dns", "package", "rust"]
not_affected_if: ["authoritative-only", "no-dnssec-validation"]
published_at: "2026-11-08T02:16:54+00:00"
first_seen_at: "2026-11-08T02:21:13+00:00"
updated_at: "2026-11-08T02:24:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123597", "first_seen_at": "2026-11-08T02:21:13+00:00"}]
exploit_sources: []
---

# Hickory DNS: transient DS lookup errors cached, causing zone-wide SERVFAIL

Link for people: https://infrastack.ai/live/CVE-2026-123597 (this .md is for agents)

Hickory DNS's DNSSEC validator caches temporary DS lookup failures (SERVFAIL, REFUSED, timeout) as bogus validation results. An attacker who can induce such a failure for a child zone's DS query makes every name in that zone return SERVFAIL until the cache entry expires.

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

## How to check

- Check the `hickory-proto` and `hickory-net` versions in `Cargo.lock` or the dependency tree (`cargo tree -i hickory-proto`).
- Confirm whether the DNSSEC validating resolver (`DnssecDnsHandle`) is in use in your build.

## Fix

- `hickory-net`: `0.26.2` or later
- `hickory-proto`: move past the affected range `0.25.0-alpha.1` through `0.26.0-alpha.1` (fixed version not stated in the sources)

## Timeline

- 2026-11-08T02:21:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123597

## Documents

- [advisory] Vendor advisory: github.com https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-xv7c-h5g9-x25x
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/hickory-dns-dnssec-validation-cache-poisoning-via-transient-ds-fetch-errors

## From the sources

Hickory DNS hickory-proto 0.25.0-alpha.1 through 0.26.0-alpha.1 and hickory-net before 0.26.2 contain a logic bug in DnssecDnsHandle's DS-fetch path that caches transient DS lookup errors as Bogus DNSSEC validation verdicts. An attacker who induces a SERVFAIL, REFUSED, or timeout response to a child-zone DS sub-query causes the validator to return SERVFAIL for all names under that zone until the cache entry's TTL expires.

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