oh thanks

Hmmm, perhaps you misunderstood the concept.

If Linux happened to be the same, then it would be vulnerable then.

So why Linux is Open Source? Yeah, because everyone must be able to see, learn, and mod it. If who knows security experts found vulnerability, any person with great moral standard would do the opposite of what you said (vulnerable to hackers) which is

bring the patch. is that simple. And there it is. Linux is once again secured from evil hackers, thanks to this good hackers. And oh, that's called Security Update.

Same goes for all project. no need to be Linux specifically, or even security at all. Good person especially bug hunters, hunts the bug, bring the bug to the project master and report it to the project master. It then be fixed and everything will be fine once again. Happily ever after.

Of course, I understand that we are not always lucky. Exploits we have no idea yet, got into their hand of evil hackers, like what you said. BUT, again, this should be rare usually. Most cases, ends good, despite existed bad endings. and as always, in that bad ending, the other who is hero will save the day. WannaCry, lose.

Did I mentioned that ransomware pandemic of the bad old days? yeah. Microsoft and anyone, let me tell you. You can't do this alone. Someone out there would like to volunteer. and most of these volunteers are good hackers. they'll hunt the bug for you, so together we can make project secure. yeah!