Inconsistent interpretation of HTTP requests in py3-waitress (Alpine package)

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU33152

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 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

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

py3-waitress (Alpine package): 1.3.1-r2 - 1.4.0-r0

External links

http://git.alpinelinux.org/aports/commit/?id=bdf9e7d1c8dd8658479cd5d2032b3fbc682d2620
http://git.alpinelinux.org/aports/commit/?id=27d1b5c609ffa40740bceb1a93245bb57d8b2c2d

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.