Why do browsers not protect against scripts coming with images?

Question

I understand that this is how it goes:

Malformed Image --> Buffer Overrun --> Stack Over Flow --> Execute Malware Pushed On Stack

And though I don't a huge amount about this, I know that I have had many of these malicious scripts come with images before that have done nasty things within my browser hiding in my cache, but why does do most browsers not protect against this? Is this something exploited through vulnerabilities (if so, there seem to be far too many of them as I've had far too many of these malicious scripts)? Or why is it so difficult to have protection against this?

I just understood from here that browsers don't protect against these things and I want to know why.

Answer 1

You did answer your own question already:

Is this something exploited through vulnerabilities ... Buffer Overrun

Buffer overflows are not intended behaviour, but indeed exploitable vulnerabilities. Browsers vendors will fix B.O. when they find it => they do protect from it. The problem is, as with all vulnerabilities, someone has to recognize that there is an error in the code first.

What your chat log says, that browsers don't use some preventive additional security features which could help against an existing error being exploited (eg. because these methods have downsides too). But they will fix the errors itself.

as I've had far too many of these malicious scripts

That could have thousands of reasons, other than images with scripts. Given that you seem to think that "buffer overrun" is always the same as "stack overflow", you probably didn't recognize some of the reasons.