Exhaust vent leaking

So I have a leak behind my stove the counter top is starting to bubble up behind the stove. I've checked the roof all appears to be good there, however under the exaught vent cover on the outside of the TT is having some bubbling under where each screw hole is. I removed the cover and have the old sealer removed the question is what kind of sealer do I need to use to put the cover back on? Thanks for any help!