CVE-2026-42254Network attack vector

Cross-zone cache poisoning via parent-zone bailiwick validation

Published Apr 26, 2026 · Updated Apr 26, 2026

DNS cache poisoning in Hickory DNS hickory-recursor 0.1 through 0.25.2 allows remote attackers to redirect sibling-zone queries. DnsLru cache_response combines ANSWER, AUTHORITY, and ADDITIONAL records, validates them against the servicing parent NS pool's zone, and caches them by record name and type. A nameserver controlled under a shared parent zone can inject a sibling-zone NS record, causing later queries to use the attacker's nameserver.

CVSS severity4.0
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DNS cache poisoning in Hickory DNS hickory-recursor 0.1 through 0.25.2 allows remote attackers to redirect sibling-zone queries. DnsLru cache_response combines ANSWER, AUTHORITY, and ADDITIONAL records, validates them against the servicing parent NS pool's zone, and caches them by record name and type. A nameserver controlled under a shared parent zone can inject a sibling-zone NS record, causing later queries to use the attacker's nameserver.

The record

CVE
CVE-2026-42254
Published
Apr 26, 2026
Updated
Apr 26, 2026
Vendor
Hickory Project
Product
Hickory DNS
Classifications
CWE-706, CWE-345, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.1 <0.26

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hickory Project · Hickory DNSversion=0.1 <0.26

Published CVSS scores

4.0MITRECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-706Use of Incorrectly-Resolved Name or Reference
CWE-345Insufficient Verification of Data Authenticity
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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