---
title: "CVE-2019-19331\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2019-19331?format=md
keywords: index, follow
---

# CVE-2019-19331

Publication date 16 December 2019

Last updated 26 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**7.5 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2019-19331?format=md#impact-score)

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## Description

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).

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| knot-resolver | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 25.04 plucky | Not affected |
| 24.10 oracular | Not affected |
| 24.04 LTS noble | Not affected |
| 23.10 mantic | Not affected |
| 23.04 lunar | Not affected |
| 22.10 kinetic | Not affected |
| 22.04 LTS jammy | Not affected |
| 21.10 impish | Ignored end of life |
| 21.04 hirsute | Ignored end of life |
| 20.10 groovy | Ignored end of life |
| 20.04 LTS focal | Fixed 3.2.1-3ubuntu2.2 |
| 19.10 eoan | Ignored end of life |
| 19.04 disco | Ignored end of life |
| 18.04 LTS bionic | Vulnerable |
| 16.04 LTS xenial | Vulnerable |
| 14.04 LTS trusty | Not in release |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2019-19331?format=md#patch-details)

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| knot-resolver | * Upstream:   <https://gitlab.nic.cz/knot/knot-resolver/-/merge_requests/903> * Upstream:   <https://gitlab.nic.cz/knot/knot-resolver/-/merge_requests/899> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.5 · High

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.5 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19331)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-19331)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-19331)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-19331)

### Other references

* <https://www.openwall.com/lists/oss-security/2019/12/04/4>
* <https://www.cve.org/CVERecord?id=CVE-2019-19331>