Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16789

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Main Vulnerability Database Vulnerabilities #VU33152

Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16789

Published: December 26, 2019 / Updated: August 3, 2020


Vulnerability identifier: #VU33152
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2019-16789
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

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.


Affected software

waitress
py3-waitress (Alpine package)
python-waitress
Oracle Communications Cloud Native Core Network Function Cloud Native Environment
Fedora

How to mitigate CVE-2019-16789

Install update from vendor's website.

waitress - update to 1.4.2
py3-waitress (Alpine package) - update to 1.4.1-r0
python-waitress - addressed in versions 1.4.3-1.el7, 1.4.3-1.el8, 1.4.3-1.fc30, 1.4.3-1.fc31

External References

Related Security Bulletins