Description

Waitress is a Web Server Gateway Interface server for Python 2 and 3. When using Waitress versions 2.1.0 and prior behind a proxy that does not properly validate the incoming HTTP request matches the RFC7230 standard, Waitress and the frontend proxy may disagree on where one request starts and where it ends. This would allow requests to be smuggled via the front-end proxy to waitress and later behavior. There are two classes of vulnerability that may lead to request smuggling that are addressed by this advisory: 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; and Waitress does not support chunk extensions, however it was discarding them without validating that they did not contain illegal characters. This vulnerability has been patched in Waitress 2.1.1. A workaround is available. When deploying a proxy in front of waitress, turning on any and all functionality to make sure that the request matches the RFC7230 standard. Certain proxy servers may not have this functionality though and users are encouraged to upgrade to the latest version of waitress instead.

Weaknesses 1

Affected Products 2

References 5

• github.com https://github.com/Pylons/waitress/commit/9e0b8c801e4d505c2ffc91b891af4ba48af715e0
  PatchRelease NotesThird Party Advisory
• github.com https://github.com/Pylons/waitress/releases/tag/v2.1.1
  Release NotesThird Party Advisory
• github.com https://github.com/Pylons/waitress/security/advisories/GHSA-4f7p-27jc-3c36
  Third Party Advisory
• lists.debian.org https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html
  Mailing ListThird Party Advisory
• debian.org https://www.debian.org/security/2022/dsa-5138
  Third Party Advisory

Remediation

• github.com https://github.com/Pylons/waitress/commit/9e0b8c801e4d505c2ffc91b891af4ba48af715e0
  PatchRelease NotesThird Party Advisory