CVE-2026-123604
Received Received - Intake

Hickory DNS resolver resource exhaustion via TC response loop

Publication date: 2026-11-08

Last updated on: 2026-11-08

Assigner: VulnCheck

Description
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.

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Meta Information

Published
2026-11-08
Last Modified
2026-11-08
Generated
2026-11-08
AI Q&A
2026-11-08
EPSS Evaluated
N/A
NVD
CVE-2026-123604
EUVD
EUVD-2026-119363

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
hickory dns_hickory_resolver to 0.26.2 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-835 The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

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Executive Summary

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

Impact Analysis

This vulnerability can cause resource exhaustion on systems using the affected Hickory DNS resolver. It may lead to degraded performance, service outages, or system crashes due to excessive CPU and memory usage while handling malicious DNS responses.

Mitigation Strategies

Update Hickory DNS hickory-resolver to version 0.26.2 or later to address the unbounded retry loop in NameServerPool::try_send.

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