CVE-2019-16789

Description

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.

How to fix CVE-2019-16789

To remediate CVE-2019-16789, upgrade the affected package to a fixed version below.

• —upgrade to 1.4.1-1 or later
• —upgrade to 0.8.9-2+deb8u1 or later
• —upgrade to 1.4.2 or later
• —upgrade to 11d9e138125ad46e951027184b13242a3c1de017 or later

Is CVE-2019-16789 being exploited?

Low — EPSS is 1.0%, meaning exploitation activity has not been observed at scale.

Affected packages (4)

• from 0, < 1.4.1-1
• from 0, < 0.8.9-2+deb8u1
• from 0, < 1.4.2
• from 0, < 11d9e138125ad46e951027184b13242a3c1de017 | from 0, < 1.4.1

CVSS scores

References (17)

• ADVISORYgithub.com/advisories/GHSA-968f-66r5-5v74
• ADVISORYnvd.nist.gov/vuln/detail/CVE-2019-16789
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2019-16789
• PATCHgithub.com/Pylons/waitress
• WEB