Vulnerability CVE-2019-16786


Published: 2019-12-20   Modified: 2019-12-21

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.

Type:

CWE-444

(Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling'))

CVSS2 => (AV:N/AC:L/Au:N/C:N/I:P/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5/10
2.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
None
Partial
None
Affected software
Agendaless -> Waitress 

 References:
https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3
https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p

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