CVE-2019-16786

HIGH7.1EPSS 0.80%

HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress

Published: 12/20/2019Modified: 4/28/2026

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.

Affected packages (3)

CVSS scores

SourceVersionSeverityVector
osvCVSS 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
osvCVSS 3.1HIGH7.1CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N

References (14)