The net/http package's Request.ParseMultipartForm method starts writing to temporary files once the request body size surpasses the given "maxMemory" limit. It was possible for an attacker to generate a multipart request crafted such that the server ran out of file descriptors.
https://groups.google.com/forum/#%21msg/golang-dev/4NdLzS8sls8/uIz8QlnIBQAJ