The presence of the index of listing is a diagnostic gift for attackers. A typical 404 error might hide the vulnerability. But an index of listing confirms:
The eval-stdin.php file contains code that uses eval() to execute the contents of php://input . index of vendor phpunit phpunit src util php evalstdinphp
This write-up details the function of this file, the mechanics of the vulnerability, and the necessary remediation steps. The presence of the index of listing is
$ echo "<?php echo 'Hello, World!';" | php vendor/phpunit/phpunit/src/util/php/evalStdin.php the mechanics of the vulnerability