Heartbleed isn't a buffer overflow in the classic sense (you're not writing more to a buffer than it expects to receive), it's just that you could set read buff

Heartbleed isn't a buffer overflow in the classic sense (you're not writing more to a buffer than it expects to receive), it's just that you could set read buffer sizes that you shouldn't have been able to in a sane world. In that sense it wasn't even a "bug" (the software was doing exactly what the programmer intended), just a badly-specified protocol to begin with.