agendaless waitress CVE-2019-16789 vulnerability in Agendaless and Other Products
Published on December 26, 2019

HTTP Request Smuggling in Waitress: Invalid whitespace characters in headers

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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.

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Vulnerability Analysis

CVE-2019-16789 can be exploited with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
LOW
Integrity Impact:
HIGH
Availability Impact:
NONE

Weakness Type

What is a HTTP Request Smuggling Vulnerability?

When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.

CVE-2019-16789 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2019-16789

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2019-16789 are published in these products:

Agendaless Waitress
 
Oracle Communications Cloud Native Core Network Function Cloud Native Environment
 
Debian Linux
 
Fedora Project Fedora
 
Red Hat Openstack
 

Affected Versions

Pylons Waitress:

Vulnerable Packages

The following package name and versions may be associated with CVE-2019-16789

Package Manager Vulnerable Package Versions Fixed In
pip waitress < 1.4.2 1.4.2

Exploit Probability

EPSS
0.88%
Percentile
75.11%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.