What software would that be, and how do you know there have never been memory-related bugs and vulnerabilities in it?
Basically all C programs I use, shells, editors, terminals, etc. But I do not claim that there "never has been a memory-related bug" but that it is not "riddled with" memory-related bugs, which I would expect would have manifested in at least one segfault over all these years, which I did not observe.