Insufficiently protected credentials in HAARG HTTP::Tiny

Summary

HTTP::Tiny versions before 0.095 for Perl forward credential headers to cross-origin redirect targets. When the server returns a 3xx redirect, `_maybe_redirect` follows the `Location:` header and `_prepare_headers_and_cb` re-merges the caller's `headers` argument into the new request, without checking whether the redirect target shares an origin with the original URL. Caller-supplied `Authorization`, `Cookie` and `Proxy-Authorization` headers are therefore re-sent to whatever host the redirect names, across scheme, host or port boundaries, and including `https` to `http` downgrades that expose them in plaintext on the wire. The HTTP::Tiny POD note that "Authorization headers will not be included in a redirected request" applied only to the URL-userinfo Basic-auth path, not to headers passed explicitly by the caller.