| Description: | OpenTelemetry-Go Contrib is a collection of third-party packages for
OpenTelemetry-Go. A handler wrapper out of the box adds labels
`http.user_agent` and `http.method` that have unbound cardinality. It
leads to the server's potential memory exhaustion when many malicious
requests are sent to it. HTTP header User-Agent or HTTP method for
requests can be easily set by an attacker to be random and long. The
library internally uses `httpconv.ServerRequest` that records every
value for HTTP `method` and `User-Agent`. In order to be affected, a
program has to use the `otelhttp.NewHandler` wrapper and not filter
any unknown HTTP methods or User agents on the level of CDN, LB,
previous middleware, etc. Version 0.44.0 fixed this issue when the
values collected for attribute `http.request.method` were changed to
be restricted to a set of well-known values and other high cardinality
attributes were removed. As a workaround to stop being affected,
`otelhttp.WithFilter()` can be used, but it requires manual careful
configuration to not log certain requests entirely. For convenience
and safe usage of this library, it should by default mark with the
label `unknown` non-standard HTTP methods and User agents to show that
such requests were made but do not increase cardinality. In case
someone wants to stay with the current behavior, library API should
allow to enable it.
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