This study investigated the vulnerabilities of three operating systems: Windows 10, macOS, and Ubuntu. The analysis of secondary data obtained from the CVE and NVD databases for the study period demonstrates varying OS vulnerability. Quantitative assessment of the vulnerability (using the vulnerability score) for the investigated operating systems found consistent results in the security vulnerability of these OS. The correlation of the disclosed vulnerabilities data and the average weighted vulnerability yielded coefficients of -0.3674, -0.4081, and 0.3473 for macOS, Windows 10, and Ubuntu Linux. These results demonstrate windows 10 as having the highest security vulnerability, followed by macOS. Ubuntu Linux had the lowest vulnerability scores. These results were validated by the CVSS distribution of the vulnerability score. The results point to the impact of the popularity of OS on the number of attacks in a given period. OS used by many people tend to attract significant attacks testing their integrity, security, and safety.