agendaless waitress CVE-2019-16786 vulnerability in Agendaless and Other Products
Published on December 20, 2019

HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress

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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.

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Vulnerability Analysis

CVE-2019-16786 is exploitable 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 high impact on confidentiality, with no impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
LOW
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-2019-16786 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2019-16786

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2019-16786 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-2019-16786

Package Manager Vulnerable Package Versions Fixed In
pip waitress < 1.4.0 1.4.0

Exploit Probability

EPSS
2.55%
Percentile
83.74%

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.