transfer of access permissions between related items

Hi all,

I'm using a custom object "Product" that has a link to "Bugs". What I would like to achieve is that whenever someone submits a bug related to the product that everyone who has access to the product can access that bug.

At the moment they can only see the title (due to our enhance security setting, which we would like to keep. 

I am trying to set up a workflow rule that transfers the access permissions when the bug is linked to a product, but can't seem to make it work.

Thanks for any help

Robin