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Changelog - 2024
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22.0.0 - 2024-04-17
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- use `utime` to notify workers liveness 
- migrate setup to pyproject.toml
- fix numerous security vulnerabilities in HTTP parser (closing some request smuggling vectors)
- parsing additional requests is no longer attempted past unsupported request framing
- on HTTP versions < 1.1 support for chunked transfer is refused (only used in exploits)
- requests conflicting configured or passed SCRIPT_NAME now produce a verbose error
- Trailer fields are no longer inspected for headers indicating secure scheme
- support Python 3.12

** Breaking changes **

- minimum version is Python 3.7
- the limitations on valid characters in the HTTP method have been bounded to Internet Standards
- requests specifying unsupported transfer coding (order) are refused by default (rare)
- HTTP methods are no longer casefolded by default (IANA method registry contains none affected)
- HTTP methods containing the number sign (#) are no longer accepted by default (rare)
- HTTP versions < 1.0 or >= 2.0 are no longer accepted by default (rare, only HTTP/1.1 is supported)
- HTTP versions consisting of multiple digits or containing a prefix/suffix are no longer accepted
- HTTP header field names Gunicorn cannot safely map to variables are silently dropped, as in other software
- HTTP headers with empty field name are refused by default (no legitimate use cases, used in exploits)
- requests with both Transfer-Encoding and Content-Length are refused by default (such a message might indicate an attempt to perform request smuggling)
- empty transfer codings are no longer permitted (reportedly seen with really old & broken proxies)


** SECURITY **

- fix CVE-2024-1135

