I would bet 99% of that 3/4 (or at least the part written in C) could have been caught with testing, fuzzing, and sanitizers we have today.
"Which of the following tools do you or your team use for guideline enforcement or other code quality/analysis?"
https://www.cvedetails.com/top-50-vendors.php
Microsoft 6508/116769 = 5.5%
Apple 4502/116769 = 3.8%
Google 4110/116769 = 3.5%
total (6508 + 4502 + 4110)/116769 = 13%