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TI-2026-86736 Aliases CVE-2026-123594GHSA-fg2p-gxqh-hm83

Hickory DNS DNSSEC NSEC Validation Bypass for Empty Non-Terminals

Priority LOW 27CWE-345Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · Low
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 are affected. The NSEC validation code (CWE-345) accepts a covering NSEC whose Next Domain Name is a strict descendant of the query name as proof that the name does not exist, although it proves the name exists as an empty non-terminal. An on-path attacker can change the unsigned rcode of a signed NODATA response from NOERROR to NXDOMAIN, so validators accept forged nonexistence of the name.

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 an NSEC validation flaw that returns a secure proof for NXDOMAIN responses when the covering NSEC's Next Domain Name is a strict descendant of the query name, which actually proves the name exists as an empty non-terminal. On-path attackers can flip the unsigned rcode of a genuine signed NODATA response from NOERROR to NXDOMAIN, causing validators to accept forged nonexistence of the name.

Why it matters now

EPSS 0.0012 1st percentileScored 2026-11-08
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

Upgrade hickory-net to 0.26.2, which fixes this flaw. 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 LOW 36 LOW

    Other records, highest priority first

    • TI-2026-86748 Resource exhaustion in hickory-dns recursor via glueless NS referralsPriority LOW 38
    • TI-2026-86746 Unbounded retry loop in Hickory DNS resolver enables resource exhaustionPriority LOW 38
    • TI-2026-86730 Denial of service in Hickory DNS recursive resolver via empty poolPriority LOW 38
    Show all 36 records →

Timeline

  1. 2026-11-08 Threatist record created from CVE-2026-123594
  2. 2026-11-08 Alias added: GHSA-fg2p-gxqh-hm83
  3. 2026-11-09 Priority changed: MEDIUM → LOW

References

Advisory 1

  • TI-2025-18857 DNSSEC validation may accept broken authentication chains CVSS 4.0MEDIUM 5.7
  • TI-2026-63089 hickory-resolver before 0.26.2 DNSSEC Validation Bypass CVSS 4.0HIGH 8.7
  • 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-2026-86746 Unbounded retry loop in Hickory DNS resolver enables resource exhaustion 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