I recently pinched my brother's cat to stop him from eating a cashew seed. My cat tried eating a cashew seed I presented him with as well.
Hazelnuts and some other nuts can be highly toxic to cats and it is still unknown whether it is related to some contents of the nuts or occasional contamination with toxic moulds, so I did not let them eat the nuts.
So, besides containing too much fat to be part of a regular diet, are cashews known to be harmful to cats?