Hickory-dns 0.20.1 before 0.26.2 Panic DoS via SVCB/HTTPS Zone Parser
Affects hickory-dns 0.20.1 through 0.26.1 in applications that parse untrusted zone files containing SVCB or HTTPS records. 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? →
- 0.34% · 28th 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 0.20.1 before 0.26.2 contains a denial of service vulnerability in the hickory-proto SVCB and HTTPS record presentation format parser, which panics on malformed alpn values. Attackers can supply untrusted zone files with unbalanced quotes, consecutive commas, or invalid escapes in alpn parameters to crash parsing processes.
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 0.20.1 · 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-2026-123572
Is CVE-2026-123572 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 malicious zone file with unbalanced quotes, consecutive commas, or invalid escapes in alpn parameters can crash the process that parses it, causing a denial of service.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-123572?
hickory-dns: from 0.20.1 before 0.26.2.Source: cve.now feed data
Am I affected, and how do I check?
Versions from 0.20.1 up to but not including 0.26.2 are affected, and hickory-proto is affected from 0.20.1 through 0.26.1. The bug applies to applications that parse SVCB or HTTPS records in zone file presentation format and that parse untrusted zone files, so check the hickory-dns version in use and whether the application reads zone files from untrusted sources.Source: vulncheck.com, github.com
How do I fix CVE-2026-123572?
Upgrade hickory-dns to 0.26.2 or later, which is the fixed version listed for this vulnerability.Source: vulncheck.com, github.com