CVSS Base Score and the underlying metrics have been widely used. Recently there have been attempts to validate them. Some of the researchers have questioned the CVSS metrics based on a lack of correlation with the reported exploits and attacks. In this research, we use the independent scales used by the vulnerability reward programs (VRPs) to see if they correlate with the CVSS Base Score. We examine 1559 vulnerabilities of Mozilla Firefox and Google Chrome browsers. The results show that there is a significant correlation between the VRPs severity ratings and CVSS scores, when three level rankings are used. For both approaches, the sets of vulnerabilities identified as Critical or High severity vulnerabilities include a large number of shared vulnerabilities, again suggesting mutual conformation. The results suggest that the CVSS Base Score may be a useful metric for prioritizing vulnerabilities, and the notable lack of exploits for high severity vulnerabilities may be the result of prioritized fixing of vulnerabilities.