Vulnerability CVE-2019-16785


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

Description:
Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. 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/8eba394ad75deaf9e5cd15b78a3d16b12e6b0eba
https://github.com/Pylons/waitress/security/advisories/GHSA-pg36-wpm5-g57p

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