---
title: "CVE-2019-16786\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-2019-16786?format=md
keywords: index, follow
---

# CVE-2019-16786

Publication date 20 December 2019

Last updated 26 August 2025

---

Ubuntu priority

**Low**

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

## Cvss 3 Severity Score

**7.1 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2019-16786?format=md#impact-score)

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## Description

Waitress through version 1.3.1 would parse the Transfer-Encoding header and
only look for a single string value, if that value was not chunked it would
fall through and use the Content-Length header instead. According to the
HTTP standard Transfer-Encoding should be a comma separated list, with the
inner-most encoding first, followed by any further transfer codings, ending
with chunked. Requests sent with: "Transfer-Encoding: gzip, chunked" would
incorrectly get ignored, and the request would use a Content-Length header
instead to determine the body size of the HTTP message. This could allow
for Waitress to treat a single request as multiple requests in the case of
HTTP pipelining. This issue is fixed in Waitress 1.4.0.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| waitress | 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 | Not affected |
| 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Not affected |
| 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-2019-16786?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 |
| --- | --- |
| waitress | * Upstream:   [f11093a](https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.1 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.1 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-16786)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-16786)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-16786)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-16786)

### Other references

* <https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes>
* <https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p>
* <https://www.cve.org/CVERecord?id=CVE-2019-16786>