The below script will help to find the older wordpress version, where the current latest is 3.6.
locate wp-includes/version.php | xargs grep "wp_version = " | grep -v " = '3.6'"
locate wp-includes/version.php | xargs grep "wp_version = " | grep -v " = '3.6'" | grep -v "cpbackup" -- This will excludes cPanel backup directories, the first does not.
locate wp-includes/version.php | xargs grep "wp_version = " | grep -v " = '3.6'"
locate wp-includes/version.php | xargs grep "wp_version = " | grep -v " = '3.6'" | grep -v "cpbackup" -- This will excludes cPanel backup directories, the first does not.