# CVE-2026-123607: Hickory DNS NSEC3 closest-encloser proof unbounded loop

Source: https://junglewise.ai/threats/cve-2026-123607-hickory-dns-hickory-proto-0-25-0-alpha-3-through-0-25-2-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-08. Updated: 2026-11-08  
License: CC BY 4.0 with a link back

CVE-2026-123607 · Severity: high · CVSS 7.5 · Published 2026-11-08

Hickory DNS is a DNS resolver library used to validate DNS security signatures (DNSSEC). An attacker controlling a DNS server can craft a malicious response that triggers an infinite loop in the validation logic, causing debug builds to crash immediately or release builds to consume all available memory until the application freezes. This affects any application using Hickory DNS with DNSSEC validation enabled.

Technologies: [Hickory-Dns Hickory-Net](https://junglewise.ai/threats/technologies/hickory-dns-hickory-net), [Hickory-Dns Hickory-Proto](https://junglewise.ai/threats/technologies/hickory-dns-hickory-proto). Vendors: [Hickory-Dns](https://junglewise.ai/threats/vendors/hickory-dns).

## Quick answers

**Is CVE-2026-123607 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123607 being exploited in the wild.

**How severe is CVE-2026-123607?** High severity, with a CVSS score of 7.5, published 8 November 2026.

**Which products and versions are affected?** Hickory-Dns Hickory-Net 0.26.0-alpha.1 through 0.26.0; Hickory-Dns Hickory-Proto 0.25.0-alpha.3 through 0.25.2.

**Is there a fix for CVE-2026-123607?** Yes: fixed in hickory-net 0.26.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123607 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-123607?** 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-net 0.26.1

## Technical details

An unbounded loop exists in DnssecDnsHandle's NSEC3 closest-encloser proof validation when validating NoData or NXDomain responses. The loop assumes the QNAME is a descendant of the SOA owner and walks up the name hierarchy; when an attacker returns a cross-zone SOA record (one that is not an ancestor of the QNAME), the iterator stalls at the DNS root and never terminates, repeatedly allocating memory. The bug is reachable by any caller of DnssecDnsHandle when built with dnssec-ring or dnssec-aws-lc-rs feature, triggered by a network-reachable upstream attacker returning a specially crafted response.

## Affected products

- Hickory DNS hickory-proto 0.25.0-alpha.3 through 0.25.2
- Hickory DNS hickory-net 0.26.0-alpha.1 through 0.26.0

## Timeline

- 2026-11-08: disclosed

## References

- [https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3v94-mw7p-v465](https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-3v94-mw7p-v465)
- [https://www.vulncheck.com/advisories/hickory-dns-nsec3-closest-encloser-proof-unbounded-loop-denial-of-service](https://www.vulncheck.com/advisories/hickory-dns-nsec3-closest-encloser-proof-unbounded-loop-denial-of-service)

## Related threats

- [Hickory DNS hickory-proto denial of service in BinEncoder](https://junglewise.ai/threats/cve-2026-123608-hickory-dns-hickory-proto-from-0-3-1-before-0-26-1-contains-a)
- [Hickory DNS DNSSEC validation bypass via RRSIG Signer's Name](https://junglewise.ai/threats/cve-2026-123605-hickory-dns-hickory-proto-0-1-through-0-25-0-alpha-3-and-hickory)
- [Hickory DNS IPv4-mapped IPv6 canonicalization bypass](https://junglewise.ai/threats/cve-2026-123603-hickory-proto-and-hickory-resolver-0-26-0-before-0-26-2-hickory)
- [Hickory DNS NSEC3 comparison operator inversion](https://junglewise.ai/threats/cve-2026-123601-hickory-dns-hickory-proto-0-25-0-through-0-26-0-alpha-1-and)
- [Hickory DNS DNSSEC validation bypass in NSEC3 NODATA](https://junglewise.ai/threats/cve-2026-123600-hickory-dns-hickory-proto-0-25-0-alpha-3-through-0-25-2-and)