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Fencer Intel
high 7.5

CVE-2026-123588 json

Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool

published 2mo ago modified yesterday also EUVD-2026-119347 , GHSA-9px7-7m25-f6q2

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository hickory-dns/hickory-dns. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

The recursive resolver in Hickory DNS (all versions of the hickory-recursor crate, and hickory-resolver 0.26.0 before 0.26.2) caches an empty connection pool when it follows a referral with no glue records and all queries for the name servers' IP addresses fail. An attacker able to spoof DNS responses can make these lookups fail, causing all subsequent queries for the affected zone to fail until the cache entry expires or is evicted.

Patch / fix

  • hickory-dns hickory-dns 0.26.2
  • rust-hickory-resolver Debian 14 0.26.3-1

debian advisories DEBIAN-CVE-2026-123588

Is CVE-2026-123588 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • hickory-dns hickory-dns

Classification

Weakness
  • CWE-754 Improper Check for Unusual or Exceptional Conditions

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of hickory-dns/hickory-dns published their own advisory on GitHub. Reviewed sources take precedence over it.