Client exec is billing software written in PHP. The installed base (and therefore impact of this) is very low. A default installation contains a phpinfo.php file in one of the mail directories.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/34687/clientexec-phpinfo.txt
Source: https://packetstormsecurity.com/files/34687/clientexec-phpinfo.txt.html