CVE-2023-45142

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.