CyberGlossary

Vulnerabilities

CVSS (Common Vulnerability Scoring System)

Also known as: CVSS score

Definition

An open framework, maintained by FIRST, that produces a 0–10 severity score for a vulnerability based on its exploitation characteristics and impact.

CVSS rates vulnerabilities through three metric groups: Base (intrinsic properties like attack vector, complexity, privileges required, and CIA impact), Temporal/Threat (exploit maturity, remediation), and Environmental (adjusted for the specific deployment). The Base score, expressed both numerically and as a vector string, is what most CVE entries publish. CVSS v3.1 dominates today and v4.0 refines metrics for IoT and supplemental severity. Scores must be combined with business context, asset criticality, and EPSS or CISA KEV signals — a high CVSS does not always mean high real-world risk, and a low CVSS may still be critical in a specific environment.

Examples

  • CVE-2021-44228 (Log4Shell) — CVSS v3.1 Base 10.0 (Critical).
  • CVE-2014-0160 (Heartbleed) — CVSS v2 Base 5.0 (Medium).

Related terms