GHSA-V6X5-CG8R-VV6X Rack's multipart header parsing allows Denial of Service via escape-heavy quoted parameters

Summary Rack::Multipart::Parserhandlemimehead parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated Stringindex searches combined with Stringslice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticat...