CVE-2024-49768

Waitress is a Web Server Gateway Interface server for Python 2 and 3. A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection. However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed. Waitress 3.0.1 fixes the race condition. As a workaround, disable channel_request_lookahead, this is set to 0 by default disabling this feature.

Impact

A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining.

When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection.

However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed.

Patches

Waitress 3.0.1 fixes the race condition.

Workarounds

Disable channel_request_lookahead, this is set to 0 by default disabling this feature. For this vulnerability this value is required to be changed from the default.

For more information

If you have any questions or comments about this advisory:

• Open an issue in https://github.com/Pylons/waitress/issues (if not sensitive or security related)
• email the Pylons Security mailing list: [email protected] (if security related)

Thanks

• m4yfly and urn1ce From TianGong Team of Legendsec at Qi'anxin Group.

Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance. It has no dependencies except ones which live in the Python standard library. It runs on CPython on Unix and Windows under Python 2.7+ and Python 3.5+. It is also known to run on PyPy 1.6.0+ on UNIX. It supports HTTP/1.0 and HTTP/1.1.

Security Fix(es):

(CVE-2024-49768)

Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance. It has no dependencies except ones which live in the Python standard library. It runs on CPython on Unix and Windows under Python 2.7+ and Python 3.5+. It is also known to run on PyPy 1.6.0+ on UNIX. It supports HTTP/1.0 and HTTP/1.1.

Security Fix(es):

(CVE-2024-49768)

Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance. It has no dependencies except ones which live in the Python standard library. It runs on CPython on Unix and Windows under Python 2.7+ and Python 3.5+. It is also known to run on PyPy 1.6.0+ on UNIX. It supports HTTP/1.0 and HTTP/1.1.

Security Fix(es):

(CVE-2024-49768)

Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance. It has no dependencies except ones which live in the Python standard library. It runs on CPython on Unix and Windows under Python 2.7+ and Python 3.5+. It is also known to run on PyPy 1.6.0+ on UNIX. It supports HTTP/1.0 and HTTP/1.1.

Security Fix(es):

(CVE-2024-49768)

Waitress is a Web Server Gateway Interface server for Python 2 and 3. A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection. However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed. Waitress 3.0.1 fixes the race condition. As a workaround, disable channel_request_lookahead, this is set to 0 by default disabling this feature.

Waitress is a Web Server Gateway Interface server for Python 2 and 3. A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection. However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed. Waitress 3.0.1 fixes the race condition. As a workaround, disable channel_request_lookahead, this is set to 0 by default disabling this feature.

TuxCare rebuilt waitress to address 1 CVE. Fixed in 2.1.2.post1+tuxcare.

Waitress has a request processing race condition in HTTP pipelining with an invalid first request. (CVE-2024-49768) Waitress has a denial of service leading to high CPU usage/resource exhaustion. (CVE-2024-49769)

This update for python-waitress fixes the following issues:

• CVE-2024-49768: Fixed request processing race condition in HTTP pipelining with invalid first request when lookahead is enabled (bsc#1232556)
• CVE-2024-49769: Fixed incorrect connection clean up leads to a busy-loop and resource exhaustion (bsc#1232554)

It was discovered that Waitress could process follow up requests when receiving a specially crafted message. An attacker could use this issue to have the server process inconsistent client requests. This issue only affected Ubuntu 24.04 LTS and Ubuntu 24.10. (CVE-2024-49768)

Dylan Jay discovered that Waitress could be lead to write to an unexisting socket after closing the remote connection. An attacker could use this issue to increase resource utilization leading to a denial of service. (CVE-2024-49769)