Impact
When using Waitress 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.
- Waitress does not support chunk extensions, however it was discarding them without validating that they did not contain illegal characters
Patches
This has been fixed in Waitress 2.1.1
Workarounds
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.
References
For more information
If you have any questions or comments about this advisory:
References
zeyu2001 Analyst
Impact
When using Waitress 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:
int()to parse strings into integers, leading to+10to be parsed as10, or0x01to be parsed as1, where as the standard specifies that the string should contain only digits or hex digits.Patches
This has been fixed in Waitress 2.1.1
Workarounds
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.
References
For more information
If you have any questions or comments about this advisory:
References