agendaless waitress CVE-2019-16785 vulnerability in Agendaless and Other Products
Published on December 20, 2019

HTTP Request Smuggling: LF vs CRLF handling in Waitress

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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.

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Vulnerability Analysis

CVE-2019-16785 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 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-2019-16785 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2019-16785

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2019-16785 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-2019-16785

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

Exploit Probability

EPSS
1.02%
Percentile
76.97%

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.