CVE-2019-16785: Agendaless Waitress

High severity, CVSS 7.5. EPSS: 2.5% chance of exploitation in the next 30 days.

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.

Affected products

• Agendaless Waitress: up to and including 1.3.1
• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 30 only; version 31 only
• Oracle Communications Cloud Native Core Network Function Cloud Native Environment: version 1.10.0 only
• Red Hat Openstack: version 15 only

Published 2019-12-20. Last modified 2026-06-17.