CVE-2026-123603
Published:November 08, 2026
Updated:November 09, 2026
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.
Affected Packages
https://github.com/hickory-dns/hickory-dns.git (GITHUB):
Affected version(s) >=v0.25.0-alpha.1 <v0.26.2 || >=v0.26.0-alpha.1 <v0.26.2Fix Suggestion:
Update to version v0.26.2hickory-server (RUST):
Affected version(s) >=0.25.0-alpha.1 <0.26.2 || >=0.26.0-alpha.1 <0.26.2Fix Suggestion:
Update to version 0.26.2hickory-proto (RUST):
Affected version(s) >=0.26.0-beta.1 <0.26.2Fix Suggestion:
Update to version 0.26.2Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Improper Access Control
EPSS
Base Score:
0.17