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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.26.2
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.26.2.
- Published
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.3/10CVSS 8.3
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 30 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.26.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- hickory-dns hickory-dns
From 0.26.0-beta.1 · fixed in 0.26.2
- hickory-dns hickory-dns
From 0.25.0 · through 0.26.0-alpha.1
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123601
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: cve.now feed data
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: github.com, vulncheck.com
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: cve.now feed data
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: github.com, vulncheck.com
How do I fix CVE-2026-123601?
Upgrade to hickory-dns 0.26.2 or later. No workaround is listed in the facts.Source: github.com, vulncheck.com