Vulnerability in Hickory-Dns
CVE-2026-123596
Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 contain a DNSSEC validation flaw in the validating recursor's NSEC handler that accepts parent-side ancestor-delegation NSEC records as proof of nonexistence for names below the zone cut. An on-path attacker, rogue parent nameserver, or attacker winning a port and TXID race can deliver one forged NXDOMAIN response built from genuinely signed parent NSEC records, causing authenticated denial of existing child-zone names cached for the negative TTL.
Published .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-3r6v-f3jh-vvqm) (vendor-advisory)
- VulnCheck Advisory: Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123596?
- CVE-2026-123596 is a high-severity vulnerability in Hickory-Dns, classified under Insufficient Verification of Data Authenticity. CVSS score: 8.8/10. Published 2026-11-08.
- How severe is CVE-2026-123596?
- High severity. CVSS v3 base score is 8.8 out of 10.