---
id: CVE-2026-123604
title: >-
  Hickory DNS 0.26.0-beta.1 before 0.26.2 Resource Exhaustion DoS via
  NameServerPool::try_send TC-Retry Loop
summary: >-
  Hickory DNS hickory-resolver 0.26.0-beta.1 before 0.26.2 contains an unbounded
  retry loop in NameServerPool::try_send, which re-queues truncated (TC)
  responses without checking the answering transport or counting iterations. A
  malicious …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-835
vendor: hickory-dns
product: hickory-dns
affected:
  - hickory-dns >= 0.26.0-beta.1 < 0.26.2
published: '2026-11-08'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T01:38:31.351Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123604'
references:
  - url: >-
      https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-6w6g-hm98-mhgm
    label: GitHub Security Advisory (GHSA-6w6g-hm98-mhgm)
  - url: >-
      https://www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-resource-exhaustion-dos-via-nameserverpool-try-send-tc-retry-loop
    label: >-
      VulnCheck Advisory: Hickory DNS 0.26.0-beta.1 before 0.26.2 Resource
      Exhaustion DoS via NameServerPool::try_send TC-Retry Loop
tags:
  - cve.org
ingestedAt: '2026-11-08T02:43:18.643Z'
---

## Overview

Hickory DNS hickory-resolver 0.26.0-beta.1 before 0.26.2 contains an unbounded retry loop in NameServerPool::try_send, which re-queues truncated (TC) responses without checking the answering transport or counting iterations. A malicious authoritative server returning TC=1 on every transport keeps the resolver spinning on a persistent TCP connection until the 5-second request deadline expires, causing resource exhaustion.

## Affected

- `hickory-dns >= 0.26.0-beta.1 < 0.26.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.