CVE-2019-16786
HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress
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.
How to fix CVE-2019-16786
To remediate CVE-2019-16786, upgrade the affected package to a fixed version below.
- —upgrade to 1.4.1-1 or later
- —upgrade to 1.4.0 or later
- —upgrade to f11093a6b3240fc26830b6111e826128af7771c3 or later
Is CVE-2019-16786 being exploited?
Low — EPSS is 0.8%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.4.1-1
- from 0, < 1.4.0
- from 0, < f11093a6b3240fc26830b6111e826128af7771c3 | from 0, < 1.3.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N |
| osv | CVSS 3.1 | HIGH7.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N |