{"id":"CVE-2026-123596","title":"Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC","summary":"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…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-345"],"vendor":"hickory-dns","product":"hickory-dns","affected":["hickory-dns <= 0.26.0-alpha.1","hickory-dns >= 0.26.0-beta.1 < 0.26.2"],"published":"2026-11-08","updated":"2026-11-08","sourceUpdated":"2026-11-08T01:38:25.747Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-123596","references":[{"url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3r6v-f3jh-vvqm","label":"GitHub Security Advisory (GHSA-3r6v-f3jh-vvqm)"},{"url":"https://www.vulncheck.com/advisories/hickory-dns-through-0.26.0-alpha.1-dnssec-validation-bypass-via-ancestor-delegation-nsec","label":"VulnCheck Advisory: Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC"}],"tags":["cve.org"],"ingestedAt":"2026-11-08T02:43:18.649Z","slug":"CVE-2026-123596","body":"## Overview\n\nHickory 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.\n\n## Affected\n\n- `hickory-dns <= 0.26.0-alpha.1`\n- `hickory-dns >= 0.26.0-beta.1 < 0.26.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}