New features are being added into mobile devices such as smart phones and tablets every day. Previously, people only used the phone for voice communication, but nowadays it allows almost any kind of internet operations even when travelling from one place to another. Smart phones and tablets are known to perform these operations through operating systems and application programs. Vulnerabilities may exist in the operating system or application software that allow these devices to be exploited by malicious users or hackers, by copying or deleting all of the data contained on them. For this reason, remediating the security vulnerabilities on operating systems is extremely important. In this study, a new database was created by querying security vulnerabilities of the most preferred operating systems on smart phones and tablets from National Vulnerability Database of the US and CVEDETAILS. With regard to vulnerabilities, CVSS scoring system, created by FIRST and used for scoring them, was examined in the light of re-scoring them. The analysis of security of the operating systems was done with quantitative methods. Eventually, it is aimed to conduct vulnerability analysis of smart phone and tablet operating systems.