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.
web.archive.org/web/20170701212357/http://phpunit.vulnbusters.com/
www.securityfocus.com/bid/101798
www.securitytracker.com/id/1039812
github.com/sebastianbergmann/phpunit/commit/284a69fb88a2d0845d23f42974a583d8f59bf5a5
github.com/sebastianbergmann/phpunit/pull/1956
security.gentoo.org/glsa/201711-15
www.oracle.com/security-alerts/cpuoct2021.html