Hickory DNS 0.26.0-beta.1 before 0.26.2 DNSSEC Validation Bypass via Missing RFC 6840 Checks
Affects hickory-net 0.26.0-beta.1 through 0.26.1 and hickory-proto up to and including 0.26.0-alpha.1 in DNSSEC validation of insecure delegations. No vendor rating is given. 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.
- Last modified
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.13% · 2nd percentile
- 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-net 0.26.0-beta.1 before 0.26.2 and hickory-proto through 0.26.0-alpha.1 fail to verify, per RFC 6840 §4.4, that an NSEC or NSEC3 record denying a DS RRset also proves the delegation's NS record exists. Attackers can reuse child-side NSEC or NSEC3 records to fake an insecure delegation and forge child-zone records.
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
- Severity8.2/10CVSS 8.2
- 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
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-2026-123591
Is CVE-2026-123591 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?
When validating an insecure delegation, Hickory DNS does not apply the RFC 6840 section 4.4 check. That check requires the NSEC or NSEC3 record proving no DS record exists to also show that the delegation's NS record exists or could exist. Without it, a forged proof can make a secure delegation look insecure, which can enable forgery of records in the child zone.Source: github.com
Which versions are affected by CVE-2026-123591?
hickory-dns: from 0.26.0-beta.1 before 0.26.2. hickory-dns: through 0.26.0-alpha.1.Source: cve.now feed data
Am I affected, and how do I check?
Affected are hickory-net 0.26.0-beta.1 through 0.26.1, and hickory-proto up to and including 0.26.0-alpha.1. To check a project, look at the hickory-net or hickory-proto version in its Cargo.lock or dependency tree.Source: github.com
How do I fix CVE-2026-123591?
Upgrade hickory-net to 0.26.2, the listed fixed version. The advisory lists no workaround.Source: github.com