These attacks are getting more and more creative. I begin to think that there is no such thing as perfect security in a world that constantly demands new features.
You're right that there's a constant tension between features and security.
It really is a matter of features and how they're implemented.
Good luck picking a byte that can exploit a 7400.
One can always take the device and turn it on for oneself.
If one can't exploit the device, one can resort to rubber-hose cryptanalysis.
Security doesn't exist in isolation. AKA. there's always a way.
If you're talking about making a browser secure against internet-based attacks, there is not always a way. This type of security is merely extremely, overwhelmingly difficult.