Disabled control characters and space in header names. Control characters (0x00-0x1f, 0x7f), space, and colon were never allowed in header names. The only somewhat valid use is header continuation which nginx never supported and which is explicitly obsolete by RFC 7230. Previously, such headers were considered invalid and were ignored by default (as per ignore_invalid_headers directive). With this change, such headers are unconditionally rejected. It is expected to make nginx more resilient to various attacks, in particular, with ignore_invalid_headers switched off (which is inherently unsecure, though nevertheless sometimes used in the wild).

scgi_param  REQUEST_METHOD     $request_method;
scgi_param  REQUEST_URI        $request_uri;
scgi_param  QUERY_STRING       $query_string;
scgi_param  CONTENT_TYPE       $content_type;

scgi_param  DOCUMENT_URI       $document_uri;
scgi_param  DOCUMENT_ROOT      $document_root;
scgi_param  SCGI               1;
scgi_param  SERVER_PROTOCOL    $server_protocol;
scgi_param  REQUEST_SCHEME     $scheme;
scgi_param  HTTPS              $https if_not_empty;

scgi_param  REMOTE_ADDR        $remote_addr;
scgi_param  REMOTE_PORT        $remote_port;
scgi_param  SERVER_PORT        $server_port;
scgi_param  SERVER_NAME        $server_name;