BREAKING NEWS: The Pope is catholic.
Honestly BOAC.
I've said it once and I've said it again.
Software is written by human beings.
The more lines of code in a piece of software, the greater the risk of bugs in the code.
More complex pieces of software have a great number of interdependencies with other software written by other people (crypto libraries etc.).
Mac, Linux, Windows .... even the infamous OpenBSD. Only an idiot would claim their software to be invincible, as time and time again, it's proven that it's not a case of if.... but when.
What differentiates the software developers is not whether there are bugs in their code, but the overall quality of their code......how many bugs are found, the seriousness of the bugs, and how the bugs are dealt with etc. etc.