as a reverse proxy, a 100 continue response is sent prematurely when a request contains expects: 100-continue
|||Apache2 Web Server||
This effects trusty, xenial and current httpd trunk.
As a reverse proxy, a 100 continue response is sent prematurely when a request contains expects: 100-continue. This causes the requesting client to send a body. The apache httpd proxy will then read the body and attempt to send it to the backend, but the backend already sent an error and should be allowed to NOT read the remaining request body, which never should have existed. When the backend does not read the request body mod_proxy_pass errors and returns a 500 error to the client. The client never receives the correct error message.