This long-standing security issue resides in older versions of , a popular unit testing framework for PHP applications.

: Run composer install --no-dev when deploying to production to ensure testing frameworks like PHPUnit are not installed on live servers.

The ability to evaluate code dynamically, as provided by scripts like EvalStdin.php , can be both powerful and perilous. Allowing the execution of arbitrary code can lead to code injection attacks, a form of security vulnerability that could enable attackers to execute unwanted actions on your system. Hence, exposing or using such functionality in insecure ways can put applications and systems at risk.

This command evaluates the PHP code and returns the result of the strlen() function.

PHPUnit Remote Code Execution (CVE-2017-9841) ... PHPUnit is a programmer-oriented testing framework for PHP. Util/PHP/eval-stdin. Undetected HackTheBox WalkThrough - Ethicalhacs.com

: This vulnerability allows an unauthenticated attacker to execute arbitrary PHP code by sending a HTTP POST request to the eval-stdin.php file.