CVE-2019-16789

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.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=947433&gt;