What is CVE-2026-123591?

CVE-2026-123591 is a medium-severity vulnerability in Hickory-Dns, classified under Insufficient Verification of Data Authenticity. CVSS score: 5.9/10. Published 2026-11-08.

How severe is CVE-2026-123591?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Hickory-Dns

CVE-2026-123591

Hickory DNS hickory-net 0.26.0-beta.1 before 0.26.2 and hickory-proto through 0.26.0-alpha.1 fail to verify, per RFC 6840 §4.4, that an NSEC or NSEC3 record denying a DS RRset also proves the delegation's NS record exists. Attackers can reuse child-side NSEC or NSEC3 records to fake an insecure delegation and forge child-zone records.

Published 2026-11-08.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.001 (2.9th percentile), scored 2026-11-09.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 2.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Hickory-Dns

Weakness classification (CWE)

CWE-345 — Insufficient Verification of Data Authenticity

References

github.com/hickory-dns/hickory-dns/security/advisories/GHSA-7php-9j59-g3ch (vendor-advisory)
www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-dnssec-val… (third-party-advisory)

Frequently asked questions

What is CVE-2026-123591?: CVE-2026-123591 is a medium-severity vulnerability in Hickory-Dns, classified under Insufficient Verification of Data Authenticity. CVSS score: 5.9/10. Published 2026-11-08.
How severe is CVE-2026-123591?: Medium severity. CVSS v3 base score is 5.9 out of 10.