Uncontrolled resource consumption in github.com/prometheus/client_golang

The Prometheus client_golang HTTP server is vulnerable to a denial of service attack when handling requests with non-standard HTTP methods.

In order to be affected, an instrumented software must use any of the promhttp.InstrumentHandler* middleware except RequestsInFlight; not filter any specific methods (e.g GET) before middleware; pass a metric with a “method” label name to a middleware; and not have any firewall/LB/proxy that filters away requests with unknown “method”.