Hickory-DNS 0.26.0 before 0.26.2 UDP Client Denial of Service via Spoofed Responses
Affects hickory-net 0.26.0 through 0.26.1 when the client UDP connection receives a malformed datagram while awaiting a name server reply. 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? →
- 0.37% · 30th 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
The hickory-net crate in Hickory DNS 0.26.0 before 0.26.2 stops listening and returns an error when a client UDP connection receives a datagram that cannot be parsed as a DNS message. Remote attackers who guess the query's source port, without knowing the transaction ID, can spoof malformed responses to abort client queries, causing denial of service.
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 · 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-2026-123584
Is CVE-2026-123584 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 a client's UDP connection is waiting for a reply from a name server and receives an unparseable datagram, it stops listening, which aborts the client's queries. The advisory describes this as a denial of service that a remote attacker can trigger by spoofing malformed responses.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-123584?
hickory-dns: from 0.26.0 before 0.26.2.Source: cve.now feed data
Am I affected, and how do I check?
The advisory lists hickory-net versions 0.26.0 through 0.26.1 as affected, with the fix in 0.26.2. To check an installed version, look at the hickory-net version in the build or dependency manifest.Source: vulncheck.com, github.com
How do I fix CVE-2026-123584?
Upgrade to hickory-net 0.26.2, which is the fixed version named in the advisory.Source: vulncheck.com, github.com