Vulnerability scanning is an automated methodology for identifying known security weaknesses in systems, networks, applications, and configurations. Scanners compare discovered assets against databases of known vulnerabilities (CVEs), misconfigurations, and security policy violations to produce prioritized reports of findings that require remediation.
Unlike penetration testing, vulnerability scanning does not attempt to exploit weaknesses. It is a non-invasive assessment technique designed for regular, repeatable execution across an organization's entire attack surface.
Vulnerability scanning operates in several phases. Asset discovery identifies live hosts, open ports, and running services across the target scope. Service enumeration fingerprints software versions, operating systems, and application frameworks. Vulnerability detection compares discovered components against vulnerability databases using version matching, banner grabbing, and authenticated checks that inspect installed patches and configurations.
Authenticated scans use credentials to log into systems and perform deeper inspection, dramatically reducing false positives and uncovering vulnerabilities that external scans miss. Network scanners like Nessus, Qualys, and OpenVAS handle infrastructure, while application scanners like OWASP ZAP and Acunetix focus on web vulnerabilities including injection flaws, cross-site scripting, and authentication weaknesses.
Results are prioritized using CVSS scores, asset criticality, and exploit availability. Modern vulnerability management platforms integrate threat intelligence to highlight vulnerabilities actively exploited in the wild, enabling risk-based prioritization. Scan results feed into ticketing systems for remediation tracking, with SLAs based on severity and asset importance.
Vulnerability scanning is the foundation of any vulnerability management program. It provides continuous visibility into an organization's security posture across all assets. Regular scanning satisfies compliance requirements for frameworks like PCI DSS, NIST, and CIS Controls while enabling teams to identify and fix weaknesses before attackers discover them.