Order by not registered users and for products in disabled categories
I'm experiencing a really strange issue on a 220.127.116.11 Magento installation. This installation is regularly patched and it has some limitations by groups. I installed an extension that hides prices and "add to cart" for not registered users and users must be activated before they can buy something and it is configured to not allow checkout to not registered users.
What happens sometime is that a non registered user can apply and finalize an order and in what is more strange, he was able to add to cart a product that is part of an hidden category.
I checked the category is not visible and I also checked that if I'm not registered I cannot see the cart and add products to it... So it's really really strange.
Do you have some ideas about the way those customers uses to make orders? Is there some alternative ways I'm not considering in your opinion?