CVE-2026-123596

high

Description

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.

References

https://www.vulncheck.com/advisories/hickory-dns-through-0.26.0-alpha.1-dnssec-validation-bypass-via-ancestor-delegation-nsec

https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3r6v-f3jh-vvqm

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-119355

Details

Source: Mitre, NVD

Published: 2026-11-08

Updated: 2026-11-08

Risk Information

CVSS v2

Base Score: 9

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 8.7

Vector: 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

Severity: High

EPSS

EPSS: 0.00185