Just saw this post. It was suggested that "/" should not be used as it might open up more directories than you want to. Better be specific, so it should be:
Text Formatted Code
<Directory /home/httpd/vhosts/domain.net/httpdocs>
php_admin_value open_basedir none
</Directory>
<Directory /home/httpd/vhosts/domain.net/httpdocs>
php_admin_value open_basedir /home/httpd/vhosts/domain.net
</Directory>
You also need to create one for vhost_ssl.conf changing httpdocs to httpsdocs.