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[SECURITY] [DLA 3000-1] waitress security update

Debian LTS Advisory DLA-3000-1                debian-lts@lists.debian.org
https://www.debian.org/lts/security/                       Stefano Rivera
May 12, 2022                                  https://wiki.debian.org/LTS

Package        : waitress
Version        : 1.0.1-1+deb9u1
CVE ID         : CVE-2019-16785 CVE-2019-16786 CVE-2019-16789 CVE-2019-16792
Debian Bug     : 1008013

Waitress is a Python WSGI server, an application server for Python web apps.

Security updates to fix request smuggling bugs, when combined with another http
proxy that interprets requests differently. 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 can result in cache
poisoning or unexpected information disclosure.


    Only recognise CRLF as a line-terminator, not a plain LF. Before this
    change waitress could see two requests where the front-end proxy only saw


    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.  This could allow for Waitress
    to treat a single request as multiple requests in the case of HTTP


    Specially crafted requests containing special whitespace characters in the
    Transfer-Encoding header would get parsed by Waitress as being a chunked
    request, but a front-end server would use the Content-Length instead as the
    Transfer-Encoding header is considered invalid due to containing invalid
    characters.  If a front-end server does HTTP pipelining to a backend
    Waitress server this could lead to HTTP request splitting which may lead to
    potential cache poisoning or unexpected information disclosure.


    If two Content-Length headers are sent in a single request, Waitress would
    treat the request as having no body, thereby treating the body of the
    request as a new request in HTTP pipelining.


    There are two classes of vulnerability that may lead to request smuggling
    that are addressed by this advisory:
    1. The use of Python's int() to parse strings into integers, leading to +10
       to be parsed as 10, or 0x01 to be parsed as 1, where as the standard
       specifies that the string should contain only digits or hex digits.
    2. Waitress does not support chunk extensions, however it was discarding
       them without validating that they did not contain illegal characters.

For Debian 9 stretch, these problems have been fixed in version

We recommend that you upgrade your waitress packages.

For the detailed security status of waitress please refer to
its security tracker page at:

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS

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