Util/PHP/eval-stdin.php in PHPUnit before 4.8.28 and 5.x before 5.6.3 allows remote attackers to execute arbitrary PHP code via HTTP POST data beginning with a "<?php " substring, as demonstrated by an attack on a site with an exposed /vendor folder, i.e., external access to the /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php URI.
Created php-phpunit-PHPUnit tracking bugs for this issue:
Affects: epel-6 [bug 1795616]
PHPUnit is a developer tool
And if people deploy web app with developer stuff.... yes they are unsecure.