---
title: "CVE-2019-20637\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-2019-20637?format=md
keywords: index, follow
---

# CVE-2019-20637

Publication date 8 April 2020

Last updated 25 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-2019-20637?format=md#impact-score)

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## Description

An issue was discovered in Varnish Cache before 6.0.5 LTS, 6.1.x and 6.2.x
before 6.2.2, and 6.3.x before 6.3.1. It does not clear a pointer between
the handling of one client request and the next request within the same
connection. This sometimes causes information to be disclosed from the
connection workspace, such as data structures associated with previous
requests within this connection or VCL-related temporary headers.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| varnish | 22.04 LTS jammy | Not affected |
| 21.10 impish | Not affected |
| 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Fixed 6.2.1-2ubuntu0.1 |
| 19.10 eoan | Ignored end of life |
| 18.04 LTS bionic | Fixed 5.2.1-1ubuntu0.1 |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## 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 | High |
  | Integrity impact | None |
  | Availability impact | None |
* Scores

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

**Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-20637)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-20637)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-20637)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-20637)

### Related Ubuntu Security Notices (USN)

+ [USN-5474-1](https://usn.ubuntu.com/USN-5474-1)
+ Varnish Cache vulnerabilities
+ 8 June 2022

### Other references

* <http://varnish-cache.org/security/VSV00004.html#vsv00004>
* <https://github.com/varnishcache/varnish-cache/commit/bd7b3d6d47ccbb5e1747126f8e2a297f38e56b8c>
* <https://www.cve.org/CVERecord?id=CVE-2019-20637>