golang: net/http/httputil: NewSingleHostReverseProxy - omit X-Forwarded-For not working

A flaw was found in net/http/httputil golang package. When httputil.ReverseProxy.ServeHTTP is called with a Request.Header map containing a nil value for the X-Forwarded-For header, ReverseProxy could set the client IP incorrectly. This issue may affect confidentiality...