CGI scripts need certain file permissions to be set if they are to work properly. In general, CGI scripts need to have permissions set at 755 (rwxr-xr-x), although PHP files only need 644 (rw-r–r–).
The folders containing CGI scripts also need certain permissions. In particular, if a folder has very lax permissions, such as 777 (rwxrwxrwx), the web servers will not execute the scripts contained in it. Folders containing CGI scripts should ideally have permissions of 711 (rwx–x–x). This also applies to the folders that contain the first folder, if you have a multi-level folder structure, although 755 for folders is also fine.