Main Vulnerability Database Vulnerabilities #VU33151

#VU33151 Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16785

Published: December 21, 2019 / Updated: August 3, 2020

Vulnerability identifier: #VU33151

Vulnerability risk: Medium

CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

CVE-ID: CVE-2019-16785

CWE-ID: CWE-444

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerable software:
waitress

Software vendor:
Pylons Project

Description

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

Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.

Remediation

Install update from vendor's website.

#VU33151 Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16785

Description

Remediation

External links