PHPUnit is the de facto standard testing framework for the PHP programming language. In 2017, a critical vulnerability was disclosed allowing unauthenticated attackers to execute arbitrary PHP code on a server simply by sending an HTTP POST request to a specific file.
If you see safe_test in the response, .
If your development environment requires an older version of PHPUnit, ensure you have updated to the patched micro-versions where this file was removed or secured (e.g., version 4.8.28+ or 5.6.3+). Checking for Compromise index of vendor phpunit phpunit src util php evalstdinphp