Actively probing running networks and applications to identify open ports, unpatched software versions, and known weaknesses.

What is vulnerability scanning?

Vulnerability scanning is an automated security process that probes your infrastructure, applications, and network configurations to find known weaknesses. A vulnerability scanner works by comparing what it discovers about your environment against databases of known vulnerabilities, like the CVE (Common Vulnerabilities and Exposures) list, and generating a report of what needs fixing.

There are several types of vulnerability scans, each targeting a different layer of your stack:

  • Network scanning checks hosts, open ports, running services, and network configurations for known flaws
  • Application scanning tests web applications and APIs for issues like injection flaws, authentication weaknesses, and insecure configurations
  • Cloud configuration scanning (often part of CSPM) evaluates your cloud resources against security benchmarks
  • Host-based scanning examines individual servers or endpoints for missing patches, outdated software, and insecure settings
  • Container scanning checks container images and registries for vulnerabilities in base images and dependencies

Most modern scanners combine several of these into a single platform, though the depth and accuracy varies widely.

How vulnerability scanning works

The typical scanning process follows a straightforward pattern:

  1. Discovery. The scanner identifies live assets, open ports, and running services in your environment.
  2. Detection. It compares what it finds against a vulnerability database (CVE, NVD, or vendor-specific feeds) to identify known weaknesses.
  3. Classification. Each finding gets scored for severity, usually using CVSS (Common Vulnerability Scoring System) ratings from 0 to 10.
  4. Reporting. Results are compiled into a report showing what was found, where, and how severe it is.

The key distinction from penetration testing: vulnerability scanners identify potential weaknesses but don't attempt to exploit them. A pen test goes further by actively trying to break in, which provides more confidence in findings but takes significantly more time and expertise.

Why vulnerability scanning matters for startups

Over 38,000 new vulnerabilities were reported in 2025, and attackers are exploiting them faster than ever. For a startup with a small team, staying on top of that volume without automated scanning is impossible.

Here's why it deserves priority:

  1. Continuous visibility. Your attack surface changes every time someone deploys code, adds a dependency, or modifies a cloud resource. Regular scanning gives you an ongoing inventory of what's exposed, not a point-in-time snapshot.
  2. Compliance expectations. SOC 2, ISO 27001, PCI DSS, and HIPAA all require regular vulnerability assessments. Automated scanning satisfies this requirement and generates the evidence auditors want to see.
  3. Catch the obvious before attackers do. Most breaches don't exploit zero-days. They exploit known, unpatched vulnerabilities that someone forgot about. Scanning catches the things that are already public knowledge and sitting in your environment.
  4. Affordable at any stage. Unlike pen testing (which can cost $10,000+ per engagement), vulnerability scanning can run continuously for a fraction of the cost. Many tools offer free tiers or startup-friendly pricing.

How Fencer helps with vulnerability scanning

Fencer runs automated vulnerability scanning across your full stack: cloud infrastructure, source code, dependencies, and external-facing assets. Instead of managing separate tools for each layer, Fencer consolidates scanning into a single platform.

What makes Fencer's approach different:

  • Risk-based prioritization. Fencer doesn't just hand you a list of CVEs sorted by CVSS score. It factors in whether a vulnerability is actually reachable in your environment, whether there's a known exploit in the wild (using KEV and EPSS data), and what the blast radius would be if exploited.
  • Full stack, one dashboard. Cloud misconfigurations, code vulnerabilities, outdated dependencies, and exposed services all show up in the same view. No more cross-referencing four different tools to understand your risk posture.
  • Compliance-ready output. Every scan maps findings to the specific SOC 2 or ISO 27001 controls they affect, and evidence syncs automatically to your GRC tool.