[JENKINS:SECURITY-2292] XXE vulnerability on agents in `mstest`

mstest 1.0.0 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks.

This allows attackers able to control the contents of the report file for the 'Publish MSTest test result report' post-build step to have agent processes parse a crafted file that uses external entities for extraction of secrets from the Jenkins agent or server-side request forgery.

NOTE: Because Jenkins agent processes usually execute build tools whose input (source code, build scripts, etc.) is controlled externally, this vulnerability only has a real impact in very narrow circumstances: when attackers can control XML files, but are unable to change build steps, Jenkinsfiles, test code that gets executed on the agents, or similar.

As of publication of this advisory, there is no fix.