# CVE-2026-123607: Hickory DNS NSEC3 Closest-Encloser Proof Unbounded Loop Denial of Service

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

Hickory DNS hickory-proto 0.25.0-alpha.3 through 0.25.2 and hickory-net before 0.26.1 contain an unbounded loop vulnerability in DnssecDnsHandle NSEC3 closest-encloser proof validation when the SOA owner is not an ancestor of the QNAME. Upstream attackers can return NoData or NXDomain responses with a cross-zone SOA record to panic debug builds or exhaust memory in release builds.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- hickory-dns / hickory-dns (hickory-proto): ≥ 0.25.0-alpha.3; ≤ 0.25.2 (affected, semver). Source: CNA: VulnCheck
- hickory-dns / hickory-dns (hickory-net): ≥ 0.26.0-alpha.1; < 0.26.1 (affected, semver); 0.26.1 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-835

## 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-3v94-mw7p-v465 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/hickory-dns-nsec3-closest-encloser-proof-unbounded-loop-denial-of-service (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123607; retrieved 2026-11-08; source updated 2026-11-08

Revision: d617a3eb88e67e9104815e0c974259fa8718a7793697e094201770b7f35e6f25

Canonical: https://y2.dev/cve/CVE-2026-123607

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