The Common Vulnerability Scoring System (CVSS) provides an open framework for communicating the characteristics and impacts of IT vulnerabilities. The National Vulnerability Database (NVD) provides specific CVSS scores for virtually all publicly known vulnerabilities. Federal agencies can use the Federal Information Processing Standards (FIPS) 199 security categories with the NVD CVSS scores to obtain impact scores that are tailored to each agency's environment. CVSS consists of three groups: Base, Temporal and Environmental. Each group produces a numeric score ranging from 0.0 to 10.0, and a vector, a compressed textual representation that reflects the values used to derive the score. The Base group represents the intrinsic qualities of a vulnerability. The Temporal group reflects the characteristics of a vulnerability that change over time. The Environmental group represents the characteristics of a vulnerability that are unique to any user's environment. CVSS enables IT managers, vulnerability bulletin providers, security vendors, application vendors and researchers to all benefit by adopting this common language of scoring IT vulnerabilities.