CVE-2019-16786: Agendaless Waitress

High severity, CVSS 7.5. EPSS: 2.4% chance of exploitation in the next 30 days.

Waitress through version 1.3.1 would parse the Transfer-Encoding header and only look for a single string value, if that value was not chunked it would fall through and use the Content-Length header instead. According to the HTTP standard Transfer-Encoding should be a comma separated list, with the inner-most encoding first, followed by any further transfer codings, ending with chunked. Requests sent with: "Transfer-Encoding: gzip, chunked" would incorrectly get ignored, and the request would use a Content-Length header instead to determine the body size of the HTTP message. This could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining. This issue is fixed in Waitress 1.4.0.

Affected products

• Agendaless Waitress: before 1.3.1 (fixed in 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.