Quick answers
- Is CVE-2026-123596 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123596 being exploited in the wild.
- How severe is CVE-2026-123596?
- High severity, with a CVSS score of 8.8, published 8 November 2026.
- Which products and versions are affected?
- Hickory-Dns Hickory-Net 0.26.0-beta.1 before 0.26.2; Hickory-Dns Hickory-Proto through 0.26.0-alpha.1.
- Is there a fix for CVE-2026-123596?
- Yes: fixed in hickory-proto: no fixed version stated; hickory-net 0.26.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123596 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-123596?
- Check whether you run Hickory-Dns Hickory-Net or Hickory-Dns Hickory-Proto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: hickory-proto: no fixed version stated; hickory-net 0.26.2
Technical details
The validating recursor's NSEC handler fails to distinguish parent-side delegation NSEC records from authoritative child-side NSECs, accepting ancestor-delegation NSEC records as proof of nonexistence for names below a zone cut. An attacker (on-path, rogue parent nameserver, or via port+TXID race) can deliver a single forged NXDOMAIN response using genuinely signed parent NSEC records; the resolver caches this denial and serves NXDOMAIN with AD=1 for legitimate child-zone names in violation of RFC 6840 §4.1, affecting subsequent queries for the negative TTL duration.
Affected products
- Hickory DNS hickory-proto through 0.26.0-alpha.1
- Hickory DNS hickory-net 0.26.0-beta.1 before 0.26.2
Timeline
- 2026-09-03: disclosed: GitHub Security Advisory GHSA-3r6v-f3jh-vvqm published
- 2026-11-08: advisory: NVD advisory published