CVE-2026-123603

Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass

Published Nov 8, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
hickory-proto and hickory-resolver 0.26.0 before 0.26.2, hickory-server 0.25.0-alpha.1 before 0.26.2, and hickory-recursor 0.25.0-alpha.3 through 0.26.0-alpha.1 fail to canonicalize IPv4-mapped IPv6 addresses when checking deny_answers, deny_server, or AccessControlSet rules. Attackers can use IPv4-mapped addresses to evade answer filtering, trigger queries to denied nameservers, or reach hickory-server library deployments on dual-stack IPv6 sockets from denied clients.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Hickory-dns
Hickory-dns hickory-dns
Vendors & Products Hickory-dns
Hickory-dns hickory-dns
Type Values Removed Values Added
Description hickory-proto and hickory-resolver 0.26.0 before 0.26.2, hickory-server 0.25.0-alpha.1 before 0.26.2, and hickory-recursor 0.25.0-alpha.3 through 0.26.0-alpha.1 fail to canonicalize IPv4-mapped IPv6 addresses when checking deny_answers, deny_server, or AccessControlSet rules. Attackers can use IPv4-mapped addresses to evade answer filtering, trigger queries to denied nameservers, or reach hickory-server library deployments on dual-stack IPv6 sockets from denied clients.
Title Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass
Weaknesses CWE-284
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 13, 2026, 3:10 AM
Reserved
Nov 6, 2026, 1:00 AM
Status
Deferred
Published
Nov 8, 2026, 2:16 AM
Modified
Nov 13, 2026, 4:17 AM