CVE-2026-123596

Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC

Published Nov 8, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
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.

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 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.
Title Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC
Weaknesses CWE-345
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 12, 2026, 1:30 PM
Reserved
Nov 6, 2026, 1:00 AM
Status
Deferred
Published
Nov 8, 2026, 2:16 AM
Modified
Nov 12, 2026, 2:17 PM