I could argue that there has actually been more serious bugs in applications written in "safe" languages (Ruby, PHP etc.) than in contemporary C applications.

I could argue that there has actually been more serious bugs in applications written in "safe" languages (Ruby, PHP etc.) than in contemporary C applications. After all, the bugs you describe is only one among many possible security problems that can arise in an application. Another big problem is ignorance of abstractions (oh, you thought this was a bytestring? turns out, it's actually dependent on your run time platform..). Straight up C is a lot more clear to read in that regard.