Vulnerability identifier: #VU33152

Vulnerability risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-16789

CWE-ID: CWE-444

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
waitress
Other software / Other software solutions

Vendor: Pylons Project

Description

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.

Mitigation
Install update from vendor's website.

Vulnerable software versions

waitress: 1.4.1

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External links
http://access.redhat.com/errata/RHSA-2020:0720
http://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
http://github.com/github/advisory-review/pull/14604
http://github.com/Pylons/waitress/commit/11d9e138125ad46e951027184b13242a3c1de017
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.