The most chaotic good thing to do would be to use the known security issues to hack into your boss' computer in the most scarry looking but harmless way. That would possibly scare them into upgrading.
With that said, you should create a paper trail on how you warned your boss, and either wash your hands of the issue or kick it up the chain, depending on how much you care.
EDIT: since it seems some people didn't get it, I meant the first option as a joke. My actual advice is the second paragraph
More like chaotic dumb. This is a good way to get fired and possibly end up with criminal charges depending on how petty the boss is. And based on how stubborn and tech illiterate they are it is likely.
As a user at a big company that needs to lock down its security, we get quarterly phishing emails that would tell you that you failed the test so to speak if you click the link. It shows how easy it is to everyday users of how easily an entire system can get compromised.
Having a "test" like this might not be bad if you run it by boss first?