CVE-2019-16789

What it is

In Waitress through version 1.4.0, if a proxy server is used in front of waitress, an invalid request may be sent by an attacker that bypasses the front-end and is parsed differently by waitress leading to a potential for HTTP request smuggling. Specially crafted requests containing special whitespace characters in the Transfer-Encoding header would get parsed by Waitress as being a chunked request, but a front-end server would use the Content-Length instead as the Transfer-Encoding header is considered invalid due to containing invalid characters. If a front-end server does HTTP pipelining to a backend Waitress server this could lead to HTTP request splitting which may lead to potential cache poisoning or unexpected information disclosure. This issue is fixed in Waitress 1.4.1 through more strict HTTP field validation.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data tampering.

Exploit odds

2.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2019-12-26 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 02:22 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.6% in the next 30 days (EPSS).
• Severity: 7.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2019-12-26 17:15 UTC

Last modified

2026-06-17 02:22 UTC

Exploit probability

2.6% · EPSS, next 30 days

Weakness

CWE-444

Record status

Modified

Affected

• Agendaless Waitress ≤ 1.4.0
• Oracle Communications Cloud Native Core Network Function Cloud Native Environment 1.10.0
• Debian Linux 9.0
• Fedoraproject Fedora 30
• Fedoraproject Fedora 31
• Redhat Openstack 15

Attack profile CVSS 3.1 · 7.1

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

Low

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2019-16789.md and follow it. Check whether this project is affected by CVE-2019-16789. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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