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Fencer Vulns
high 7.5

CVE-2019-19331 json

knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization.

published 2019-12-16 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-8952

cvss
7.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).

Patch / fix

  • nic knot_resolver 4.3.0
  • knot-resolver Debian 14, Debian 13, Debian 12 5.0.1-1

debian advisories DEBIAN-CVE-2019-19331

  • knot-resolver Ubuntu 20.04 LTS 3.2.1-3ubuntu2.2

ubuntu advisories UBUNTU-CVE-2019-19331

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • knot-resolver Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 4.3.0-r0

alpine advisories ALPINE-CVE-2019-19331

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-19331 updated cvss 7.5

knot-resolver: DNS packets taking few seconds to process with full CPU utilization leads to DoS

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.11% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-19331 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • CZ.NIC knot-resolver

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity
  • CWE-404 Improper Resource Shutdown or Release

References

Sources

Fencer Vulns 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.