Hickory DNS NSEC3 Closest-Encloser Proof Unbounded Loop Denial of Service
Hickory builds with dnssec-ring or dnssec-aws-lc-rs and DNSSEC validation are affected: hickory-proto 0.25.0-alpha.3 to 0.25.2 and hickory-net 0.26.0-alpha.1 to 0.26.0. Fixed in hickory-net 0.26.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.26.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.26.1.
- 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? →
- 42/100 · 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-alpha.3 through 0.25.2 and hickory-net before 0.26.1 contain an unbounded loop vulnerability in DnssecDnsHandle NSEC3 closest-encloser proof validation when the SOA owner is not an ancestor of the QNAME. Upstream attackers can return NoData or NXDomain responses with a cross-zone SOA record to panic debug builds or exhaust memory in release builds.
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
- Reach16/20hickory-net: 1.4M downloads a week
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 87 if added to CISA KEV
- Would score about 82 if CISA's SSVC rates exploitation active
- Would score about 47 if advisories confirm default setups are exposed
Impact
- Widely used
hickory-net has 1.4m weekly downloads.Source: crates.io
What to do
Upgrade to a fixed version: 0.26.1.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- hickory-dns hickory-dns
From 0.25.0-alpha.3 · through 0.25.2
- hickory-dns hickory-dns
From 0.26.0-alpha.1 · fixed in 0.26.1
- hickory-netcrates.io
From 0.0.0-0 · fixed in 0.26.1
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123607
Is CVE-2026-123607 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?
A flaw in how Hickory DNS checks NSEC3 closest-encloser proofs can cause an unbounded loop while validating certain NoData or NXDomain responses. A debug build can crash from a panic, and a release build can run out of memory.Source: github.com
Which versions are affected by CVE-2026-123607?
hickory-dns: from 0.25.0-alpha.3 through 0.25.2. hickory-dns: from 0.26.0-alpha.1 before 0.26.1. hickory-net (crates.io): from 0.0.0-0 before 0.26.1.Source: cve.now feed data
Am I affected, and how do I check?
Affected versions are hickory-proto 0.25.0-alpha.3 through 0.25.2 and hickory-net 0.26.0-alpha.1 through 0.26.0 that use DnssecDnsHandle. The issue applies only when the build includes the dnssec-ring or dnssec-aws-lc-rs feature and DNSSEC validation is configured. To check, look at the hickory-proto or hickory-net version in the build and at the enabled crate features and DNSSEC validation setting.Source: github.com
How do I fix CVE-2026-123607?
Update to hickory-net 0.26.1, which the advisory recommends for the fix. No workaround is listed in the facts.Source: github.com