CVE-2019-16785

What it is

Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.

At a glance

Exploitability

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

Exploit odds

2.5% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2019-12-20 23:15 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: 2.5% in the next 30 days (EPSS).
• Severity: 7.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2019-12-20 23:15 UTC

Last modified

2026-06-17 02:22 UTC

Exploit probability

2.5% · EPSS, next 30 days

Weakness

CWE-444

Record status

Modified

Affected

• Agendaless Waitress ≤ 1.3.1
• 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

High

Integrity

Low

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-2019-16785.md and follow it. Check whether this project is affected by CVE-2019-16785. 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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