Pluck CMS through 4.7.21 restricts dangerous file uploads in its admin file-management feature using a fixed blacklist in data/inc/files.php ('.php','php3','php4','php5','php6','php7','phtml','.phtm','.pht','.ph3','.ph4','.ph5','.asp','.cgi','.phar'), checked against the last 4-5 characters of the filename.
CWE-434