{"id":"UBUNTU-CVE-2019-16786","details":"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.","modified":"2025-10-24T04:47:53Z","published":"2019-12-20T23:15:00Z","upstream":["CVE-2019-16786"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2019-16786"},{"type":"REPORT","url":"https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes"},{"type":"REPORT","url":"https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2019-16786"}],"affected":[{"package":{"name":"waitress","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/waitress@0.8.10-1?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.8.9-2ubuntu1","0.8.10-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.8.10-1","binary_name":"python-waitress"},{"binary_version":"0.8.10-1","binary_name":"python3-waitress"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2019/UBUNTU-CVE-2019-16786.json"}},{"package":{"name":"waitress","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/waitress@1.0.1-1?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.1-1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.0.1-1","binary_name":"python-waitress"},{"binary_version":"1.0.1-1","binary_name":"python3-waitress"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2019/UBUNTU-CVE-2019-16786.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},{"type":"Ubuntu","score":"low"}]}