A flaw in Node.js HTTP client can cause a request desynchronization for Node.js-based forwarding proxies that rebuild outbound headers from the visible `IncomingMessage` headers while piping the orig…

Summary

A flaw in Node.js HTTP client can cause a request desynchronization for Node.js-based forwarding proxies that rebuild outbound headers from the visible `IncomingMessage` headers while piping the original body to a reused backend connection. Node.js can omit headers beyond `maxHeadersCount` / `maxHeaderPairs` from `req.headers`, `req.rawHeaders`, and `req.headersDistinct`, while still using those omitted headers internally for HTTP message framing. In particular, `Content-Length` can be hidde…