HTTP Request Smuggling Affecting python2-waitress package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.9% (76th percentile)

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  • Snyk IDSNYK-RHEL7-PYTHON2WAITRESS-16873397
  • published23 May 2026
  • disclosed20 Dec 2019

Introduced: 20 Dec 2019

CVE-2019-16786  (opens in a new tab)
CWE-444  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:7 python2-waitress.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python2-waitress package and not the python2-waitress package as distributed by RHEL. See How to fix? for RHEL:7 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1