to clarify, it is undiscovered
thats according to the periodic pattern which is never really wrong
and we could just say that we discovered unquandium (element 144) which is theoretically stronger than anything that exists in the world
we don't have access to the full amount of elements on the periodic table because some just are too costly to make and need special circumstanes for further new elements and you never know, one could be so strong it's insane
but carbon monoxide is strong
ok the strongest possible covalent bond is a 6 bond Covalency in an molecule