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TI-2026-86737 Aliases CVE-2026-123595GHSA-v96c-g4c4-84vh

DNSSEC validation bypass in Hickory DNS via NSEC3 ancestor delegation

Priority MEDIUM 53CWE-345Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-345.

Summary

Hickory DNS hickory-proto from 0.25 through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 are affected. The validating recursor's NSEC3 handler matches the closest encloser by hash alone without checking the type bitmap (CWE-345). It accepts parent-side ancestor-delegation NSEC3 records as proof of nonexistence. A remote attacker with low privileges sends one response built from genuinely signed parent NSEC3 records, causing NXDOMAIN or NODATA to be cached with AD=1 and denying resolution of existing names at and below the zone cut.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

Description from the CNA

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.

Why it matters now

Fix Fixed hickory-dns (hickory-dns): 0.26.2

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
hickory-dnshickory-dns0.25 – 0.26.0-alpha.1—No fix listedCNA
hickory-dnshickory-dns0.26.0-beta.1 to before 0.26.20.26.2Patch availableCNA
  • hickory-dns Vendorhickory-dns Affected 0.25 – 0.26.0-alpha.1 Fixed in — No fix listed CNA
  • hickory-dns Vendorhickory-dns Affected 0.26.0-beta.1 to before 0.26.2 Fixed in 0.26.2 Patch available CNA

Remediation

Upgrade hickory-net to 0.26.2, the listed fixed version. The sources list no fixed version for hickory-proto.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

  • Fix · CNA hickory-dns (hickory-dns) Fixed in 0.26.2

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    hickory-dns 0.26.2

    36 records Highest priority Priority MEDIUM 36 MEDIUM

    Other records, highest priority first

    • TI-2026-86729 DNSSEC nonexistence forgery in Hickory DNS via wraparound NSECPriority MEDIUM 54
    • TI-2026-86748 Resource exhaustion in hickory-dns recursor via glueless NS referralsPriority MEDIUM 53
    • TI-2026-86747 DNSSEC validation bypass in Hickory DNS via RRSIG signer namePriority MEDIUM 53
    Show all 36 records →

Timeline

  1. 2026-11-08 Threatist record created from CVE-2026-123595
  2. 2026-11-08 Alias added: GHSA-v96c-g4c4-84vh

References

Advisory 1

  • TI-2025-18857 DNSSEC validation may accept broken authentication chains CVSS 4.0MEDIUM 5.7
  • TI-2026-86729 DNSSEC nonexistence forgery in Hickory DNS via wraparound NSEC CVSS 4.0HIGH 8.9
  • TI-2026-86750 CPU exhaustion in Hickory DNS hickory-proto via BinEncoder name compression CVSS 4.0HIGH 8.7
  • TI-2026-86749 Hickory DNS NSEC3 validation loop enables denial of service CVSS 4.0HIGH 8.7
  • TI-2026-86748 Resource exhaustion in hickory-dns recursor via glueless NS referrals CVSS 4.0HIGH 8.7
  • TI-2026-86747 DNSSEC validation bypass in Hickory DNS via RRSIG signer name CVSS 4.0HIGH 8.7
See all 40 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences