contributor's access to portfolio items

Hi,

I understood that WP Contributor role should be able to “delete_posts”, “edit_posts” and “read” as defined at http://codex.wordpress.org/Roles_and_Capabilities#Contributor. However, I just found that a user with contributor role has access to Theme’s Portfolio Items. Not only a contributor has access to it, she can also create and publish new Portfolio Items. And same applies to Media items.

Is this a bug? How can I prevent Contributors from accessing the Portfolio Items and Media?

Thank you,