7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:N/I:P/A:N
0.003 Low
EPSS
Percentile
67.9%
Waitress 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. This brings a range of changes to harden Waitress against potential HTTP request confusions, and may change the behaviour of Waitress behind non-conformist proxies.
Waitress will now return a 501 Not Implemented error if the Transfer-Encoding
is not chunked
or contains multiple elements. Waitress does not support any transfer codings such as gzip
or deflate
.
The Pylons Project recommends upgrading as soon as possible, while validating that the changes in Waitress don't cause any changes in behavior.
Various reverse proxies may have protections against sending potentially bad HTTP requests to the backend, and or hardening against potential issues like this. If the reverse proxy doesn't use HTTP/1.1 for connecting to the backend issues are also somewhat mitigated, as HTTP pipelining does not exist in HTTP/1.0 and Waitress will close the connection after every single request (unless the Keep Alive header is explicitly sent… so this is not a fool proof security method).
access.redhat.com/errata/RHSA-2020:0720
docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
github.com/advisories/GHSA-g2xc-35jw-c63p
github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3
github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p
lists.debian.org/debian-lts-announce/2022/05/msg00011.html
lists.fedoraproject.org/archives/list/[email protected]/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7/
lists.fedoraproject.org/archives/list/[email protected]/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5/
nvd.nist.gov/vuln/detail/CVE-2019-16786
www.oracle.com/security-alerts/cpuapr2022.html
7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:N/I:P/A:N
0.003 Low
EPSS
Percentile
67.9%