OpenTelemetry dotnet is a dotnet telemetry framework. In affected versions of `OpenTelemetry.Instrumentation.Http` and `OpenTelemetry.Instrumentation.AspNetCore` the `url.full` writes attribute/tag on spans (`Activity`) when tracing is enabled for outgoing http requests and `OpenTelemetry.Instrumentation.AspNetCore` writes the `url.query` attribute/tag on spans (`Activity`) when tracing is enabled for incoming http requests. These attributes are defined by the Semantic Conventions for HTTP Spans. Up until version `1.8.1` the values written by `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` will pass-through the raw query string as was sent or received (respectively). This may lead to sensitive information (e.g. EUII - End User Identifiable Information, credentials, etc.) being leaked into telemetry backends (depending on the application(s) being instrumented) which could cause privacy and/or security incidents. Note: Older versions of `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` may use different tag names but have the same vulnerability. The `1.8.1` versions of `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` will now redact by default all values detected on transmitted or received query strings. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Affected: NuGet: OpenTelemetry.Instrumentation.Http, NuGet: OpenTelemetry.Instrumentation.AspNetCore

## Impact

`OpenTelemetry.Instrumentation.Http` writes the `url.full` attribute/tag on spans (`Activity`) when tracing is enabled for outgoing http requests and `OpenTelemetry.Instrumentation.AspNetCore` writes the `url.query` attribute/tag on spans (`Activity`) when tracing is enabled for incoming http requests.

These attributes are defined by the [Semantic Conventions for HTTP Spans](https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-spans.md).

Up until the `1.8.1` the values written by `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` will pass-through the raw query string as was sent or received (respectively). This may lead to sensitive information (e.g. EUII - End User Identifiable Information, credentials, etc.) being leaked into telemetry backends (depending on the application(s) being instrumented) which could cause privacy and/or security incidents.

Note: Older versions of `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` may use different tag names but have the same vulnerability.

## Resolution

The `1.8.1` versions of `OpenTelemetry.Instrumentation.Http` & `OpenTelemetry.Instrumentation.AspNetCore` will now redact by default all values detected on transmitted or received query strings.

Example transmitted or received query sting:

`?key1=value1&key2=value2`

Example of redacted value written on telemetry:

`?key1=Redacted&key2=Redacted`