No wallet is 100% secure except an offline wallet where you do the hashing on an abacus... Its entirely possible (likely) a 0-day exploit will be discovered and you will lose every bitcoin handled by your client...
You don't have to do hashing to maintain a wallet. 0-day exploits only work on connected machines. So when using an offline machine to keep your keys you will not lose any bitcoin to a 0-day exploit. No abacus required, just scissors for the network cable.