This question is asked approximately once per day on the dbi-users list. In this case it's a permissions problem, and tilly's addressed that.

Usually, the problem is that the LD_LIBRARY_PATH in your environment contains the path to the Oracle libraries, but for the user that runs CGI scripts (probably the user 'nobody') it doesn't.

One solution is to modify the web server's configuration to set the LD_LIBRARY_PATH environment variable to include the path to the Oracle libraries.

Another solution, the one that I prefer, is to add the path to the Oracle libraries to the /etc/ld.so.conf file, and then run ldconfig. That will make the Oracle library path available to all users.