# CVE-2026-123595: Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC3

Status: published. Published: 2026-11-08. Updated: 2026-11-08.

Hickory DNS hickory-proto 0.25 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 NSEC3 handler, which matches the closest encloser by hash alone without checking the type bitmap and so accepts parent-side ancestor-delegation NSEC3 records as proof of nonexistence. An attacker who delivers one response built from genuinely signed parent NSEC3 records can cause NXDOMAIN or NODATA to be cached with AD=1, denying resolution of existing names at and below the zone cut.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- hickory-dns / hickory-dns (hickory-proto): ≥ 0.25; ≤ 0.26.0-alpha.1 (affected, custom). Source: CNA: VulnCheck
- hickory-dns / hickory-dns (hickory-net): ≥ 0.26.0-beta.1; < 0.26.2 (affected, semver); 0.26.2 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); 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; source: CNA: VulnCheck

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-345

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-624w-vvww-xvpw (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/hickory-dns-through-0.26.0-alpha.1-dnssec-validation-bypass-via-ancestor-delegation-nsec3 (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123595; retrieved 2026-11-08; source updated 2026-11-08

Revision: 87c089256348f2591503ac5215c56be9f9a8273b96342089aa843f354da51e1e

Canonical: https://y2.dev/cve/CVE-2026-123595

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