yopass Prometheus metrics middleware allows remote memory exhaustion through unbounded method labels
The Prometheus metrics middleware in pkg/server/server.go used r.Method directly as a label value on request counter and duration histogram metrics. Since the mux catch-all route matches any HTTP method, an unauthenticated attacker can send requests with arbitrary method strings (e.g. curl -X "M1" http://host/), each creating new counter and histogram time series in the Prometheus registry. The registry's internal maps never evict entries. An attacker issuing requests with unique method …