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TI-2026-86738 Aliases CVE-2026-123596GHSA-88cx-p9f5-pr4w

DNSSEC validation bypass in Hickory DNS accepts forged NSEC proofs

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 through 0.26.0-alpha.1 and hickory-net from 0.26.0-beta.1 before 0.26.2 accept parent-side ancestor-delegation NSEC records as proof of nonexistence for names below the zone cut. An on-path attacker, a rogue parent nameserver, or an attacker who wins a port and TXID race can deliver one forged NXDOMAIN built from genuinely signed parent NSEC records. The validating recursor then caches authenticated denial of existing child-zone names for the negative TTL (CWE-345).

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

Description from the CNA

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.

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-dnsup to 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 up to 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

Update hickory-net to version 0.26.2. 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-2026-123596
  2. 2026-11-08 Alias added: GHSA-88cx-p9f5-pr4w

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