# PYSEC-2019-66 - Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the…

Source: https://junglewise.ai/threats/pysec-2019-66-waitress-through-version-1-3-1-implemented-a-may-part-of-f0ddf309  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2019-12-20  
License: CC BY 4.0 with a link back

Severity: info · Published 2019-12-20

Waitress through version 1.3.1 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. 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 issue is fixed in Waitress 1.4.0.

Technologies: [waitress (PyPI)](https://junglewise.ai/threats/technologies/waitress). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Informational severity, published 20 December 2019.

**Which products and versions are affected?** waitress (PyPI) GIT:introduced=0,fixed=8eba394ad75deaf9e5cd15b78a3d16b12e6b0eba|ECOSYSTEM:introduced=0,fixed=1.4.0.

**Is there a fix for This vulnerability?** Yes. waitress (PyPI): upgrade to 1.4.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected?** Check whether you run waitress (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- waitress (PyPI): upgrade to 1.4.0 or later

  ```sh
  pip install "waitress>=1.4.0"
  ```


## Affected products

- waitress (PyPI) GIT:introduced=0,fixed=8eba394ad75deaf9e5cd15b78a3d16b12e6b0eba|ECOSYSTEM:introduced=0,fixed=1.4.0

## Related threats

- [Waitress denial of service via unclean socket handling](https://junglewise.ai/threats/cve-2024-49769-waitress-denial-of-service-via-unclean-socket-handling)
- [Waitress has request processing race condition in HTTP pipelining with invalid first request](https://junglewise.ai/threats/cve-2024-49768-waitress-has-request-processing-race-condition-in-http-pipelining)
- [Uncaught Exception (due to a data race) leads to process termination in Waitress](https://junglewise.ai/threats/cve-2022-31015-uncaught-exception-due-to-a-data-race-leads-to-process)
- [HTTP Request Smuggling in waitress](https://junglewise.ai/threats/cve-2022-24761-http-request-smuggling-in-waitress)
- [Catastrophic backtracking in regex allows Denial of Service in Waitress](https://junglewise.ai/threats/cve-2020-5236-catastrophic-backtracking-in-regex-allows-denial-of-service-in)