Hickory DNS 0.25.0-alpha.3 through 0.25.2 Query Amplification via Cyclic Referrals
- 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? →
- 26/100 · 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 0.25.0-alpha.3 through 0.25.2 contains a query amplification vulnerability in its recursive resolver, which mishandles cyclic sibling name server referrals that lack glue records. Attackers controlling two zones whose name servers reference each other without glue records can make the recursor loop, sending many upstream queries, amplified further by zero-TTL NS 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
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
- Would score about 31 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 0.25.0-alpha.3 · through 0.25.2
- hickory-dns hickory-dns
fixed in 0.26.2
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123586
Is CVE-2026-123586 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 two zones have cyclic sibling name servers and lack the required glue records, the recursive resolver can loop and send many upstream queries. Zero-TTL NS records amplify the number of queries, which can consume resolver resources and cause denial of service.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-123586?
hickory-dns: from 0.25.0-alpha.3 through 0.25.2. hickory-dns: before 0.26.2.Source: cve.now feed data
Am I affected, and how do I check?
Hickory DNS 0.25.0-alpha.3 through 0.25.2 is affected when its recursive resolver is in use. To check, run the Hickory DNS version command on the installed build and compare it with that range.Source: vulncheck.com, github.com
How do I fix CVE-2026-123586?
Upgrade Hickory DNS to version 0.26.2 or later, which contains the fix. No workaround is listed in the facts.Source: vulncheck.com, github.com