Hickory DNS hickory-proto 0.3.1 before 0.26.1 CPU Exhaustion via BinEncoder Name Compression
Affects hickory-proto 0.3.1 through 0.26.0, where DNS messages with many records can add many name-compression labels during encoding. The fix is in 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 from 0.3.1 before 0.26.1 contains a denial of service vulnerability in BinEncoder that allows remote attackers to exhaust CPU through quadratic-time name compression. Attackers can send malicious DNS messages with many records that add many candidate labels and trigger repeated linear scans during encoding, amplifying CPU exhaustion.
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-proto: 2.6M 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-proto has 2.6m 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 0.3.1 · fixed in 0.26.1
- hickory-protocrates.io
From 0.3.1 · 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-2026-123608
Is CVE-2026-123608 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?
Encoding a DNS message that contains many records can add many candidate name-compression labels, which drives up CPU use. The result is a denial of service through CPU exhaustion during DNS message encoding.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-123608?
hickory-dns: from 0.3.1 before 0.26.1. hickory-proto (crates.io): from 0.3.1 before 0.26.1.Source: cve.now feed data
Am I affected, and how do I check?
hickory-proto versions 0.3.1 through 0.26.0 are in the affected range, and hickory-dns is listed for versions from 0.3.1 up to but not including 0.26.1. To check, look at the hickory-proto version your build uses.Source: github.com, vulncheck.com
How do I fix CVE-2026-123608?
Upgrade hickory-proto to 0.26.1 or later. The sources list no workaround.Source: github.com, vulncheck.com