CVE-2021-32715

hyper is an HTTP library for rust. hyper’s HTTP/1 server code had a flaw
that incorrectly parses and accepts requests with a Content-Length header
with a prefixed plus sign, when it should have been rejected as illegal.
This combined with an upstream HTTP proxy that doesn’t parse such
Content-Length headers, but forwards them, can result in “request
smuggling” or “desync attacks”. The flaw exists in all prior versions of
hyper prior to 0.14.10, if built with rustc v1.5.0 or newer. The
vulnerability is patched in hyper version 0.14.10. Two workarounds exist:
One may reject requests manually that contain a plus sign prefix in the
Content-Length header or ensure any upstream proxy handles
Content-Length headers with a plus sign prefix.