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Vulnerability

A weakness in a system, application, or process that could be exploited by a threat actor to gain unauthorized access or cause harm.

Security FoundationsAlso called: "security vulnerability", "security flaw", "security weakness", "vuln"

Vulnerabilities are security flaws that create risk when combined with threats and insufficient controls. Managing vulnerabilities is a continuous process essential to cybersecurity.

Why it matters

  • Most breaches exploit known vulnerabilities with available patches.
  • The average time to exploit a new vulnerability is shrinking (now under 15 days).
  • Organizations typically have thousands of vulnerabilities across their systems.
  • Prioritization is essential—you can't fix everything at once.

Vulnerability lifecycle

  1. Discovery: Vulnerability is found by researchers, vendors, or attackers.
  2. Disclosure: Reported to vendor (responsible disclosure) or publicly.
  3. Patch released: Vendor issues a fix.
  4. Exploitation: Attackers develop exploits, sometimes before patches.
  5. Remediation: Organizations apply patches and mitigations.

Severity scoring

  • CVSS (Common Vulnerability Scoring System): 0-10 scale based on exploitability and impact.
  • Critical (9.0-10.0): Immediate action required.
  • High (7.0-8.9): Prioritize patching.
  • Medium (4.0-6.9): Schedule remediation.
  • Low (0.1-3.9): Address when convenient.

Types of vulnerabilities

  • Software bugs: Buffer overflows, injection flaws, logic errors.
  • Misconfigurations: Default credentials, open ports, excessive permissions.
  • Design flaws: Weak cryptography, missing authentication.
  • Human factors: Social engineering susceptibility, weak passwords.
  • Zero-days: Unknown vulnerabilities with no available patch.

Vulnerability management process

  • Asset inventory: Know what you have to protect.
  • Scanning: Regular automated vulnerability assessments.
  • Prioritization: Risk-based ranking considering asset criticality and exploitability.
  • Remediation: Patching, configuration changes, or compensating controls.
  • Verification: Confirm vulnerabilities are actually fixed.
  • Reporting: Track metrics and communicate risk to leadership.