Apple’s Mac OS X is considered to be the most secure operating system in the world, but is not even listed on the top three vulnerable OS. Surprisingly, Microsoft’s operating systems were the least vulnerable OS, as they fall into the bottom half of the list and rank at 5th, 7th and 8th, with 36 vulnerabilities reported in all of them. Microsoft’s Internet Explorer browser lead the list with 242 total vulnerabilities, with 220 of them being rated as critical. Google Chrome browser had 124 vulnerabilities, but Adobe Flash Player improved last year with only 76 vulnerabilities reported.
Source: https://thehackernews.com/2015/02/vulnerable-operating-system.html