November 14, 2026

CVE Watchtower

CVE-2026-123603hickory-dns hickory-dns Improper Access Control

NVD

Vulnerability Summary

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.
Severity Level
MEDIUM(6.9)
Published Date
Nov 8, 2026
Last Modified
Nov 13, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.17%Probability
Root Weakness (CWE)
CWE-284: Improper Access Control ↗
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
CVSS v4.0 Base Metrics — Score 6.9 (MEDIUM)
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
Attack VectorNetwork
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)Low
Integrity (Vulnerable System)Low
Availability (Vulnerable System)None
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 6.5)
CVSS v3.1 Base Metrics — Score 6.5 (MEDIUM)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

Affected & Patched Versions

Affected Versions
  • hickory-dns hickory-dns >= 0.25.0-alpha.3 and <= 0.26.0-alpha.1
  • hickory-dns hickory-dns >= 0.26.0 and < 0.26.2
  • hickory-dns hickory-dns >= 0.25.0-alpha.1 and < 0.26.2
Patched Versions
  • hickory-dns hickory-dns 0.26.0-alpha.1
  • hickory-dns hickory-dns 0.26.2

What to do

Fix it during your normal patch cycle. No exploitation is confirmed yet.

  1. Check whether you run hickory-dns hickory-dns and which version.
  2. Update to a patched version listed above, then confirm the new version.

Timeline

  • Nov 8, 2026Published
  • Nov 13, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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External References

Data last checked: Nov 14, 2026 02:13 UTC