Hickory DNS from 0.26.0 before 0.26.2 Panic via TSIG RDATA Decoding
Only hickory-dns 0.26.0 and 0.26.1 are affected, and only in builds with overflow checks enabled, such as the dev profile. 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? →
- 0.41% · 35th 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? →
- 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 from 0.26.0 before 0.26.2 contains an integer underflow vulnerability in TSIG RDATA decoding that allows remote attackers to trigger a panic via malformed records. Attackers can send a crafted TSIG record in DNS wire format to cause unchecked subtraction underflow, crashing builds with overflow checks enabled and 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
- Severity8.7/10CVSS 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 0.26.0 · 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-2026-123571
Is CVE-2026-123571 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 crafted TSIG record can make hickory-dns panic and crash the process, which causes denial of service.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-123571?
hickory-dns: from 0.26.0 before 0.26.2.Source: cve.now feed data
Am I affected, and how do I check?
The hickory-dns versions 0.26.0 through 0.26.1 (hickory-proto) are affected. The panic occurs only in builds with overflow checks enabled, such as the dev profile, so check the hickory-dns version in use and whether the build profile enables overflow checks.Source: github.com, vulncheck.com
How do I fix CVE-2026-123571?
Upgrade to hickory-dns 0.26.2, the fixed version. No workaround is listed in the facts.Source: github.com, vulncheck.com