{"id":"CVE-2019-16786","url":"https://www.cyber-defence.io/tools/cve/CVE-2019-16786","generatedAt":"2026-10-27T23:25:54.286Z","title":"This could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining.","description":"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.","published":"2019-12-20T23:15:11.000Z","lastModified":"2026-06-17T02:22:48.000Z","status":"Modified","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"cwe":["CWE-444"],"affected":["agendaless/waitress","oracle/communications cloud native core network function cloud native environment","debian/debian linux","fedoraproject/fedora","redhat/openstack"],"epss":{"score":0.02379,"percentile":0.83772,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (2.38%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://access.redhat.com/errata/RHSA-2020:0720","tags":["Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes","tags":["Release Notes","Vendor Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3","tags":["Patch","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p","tags":["Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html","tags":["Mailing List","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7/","source":"security-advisories@github.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5/","source":"security-advisories@github.com"},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":["Patch","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://access.redhat.com/errata/RHSA-2020:0720","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-16786","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}