A weakness in your code, software, or system that an attacker could exploit, like an outdated library or an exposed secret.

What is a vulnerability?

A vulnerability is any weakness that could be exploited to compromise the security of a system. In software, vulnerabilities are typically bugs or design flaws that allow an attacker to do something the system's creators didn't intend: read data they shouldn't access, execute code they shouldn't run, or bypass controls that should have stopped them.

Vulnerabilities are cataloged using the Common Vulnerabilities and Exposures (CVE) system, which assigns a unique identifier (like CVE-2024-3094) to each publicly disclosed vulnerability. As of 2025, the CVE database contains over 200,000 entries, and new vulnerabilities are published at a rate of roughly 80 to 100 per day.

Not all vulnerabilities are equal. They vary across several dimensions:

  • Severity. How much damage could exploitation cause? A vulnerability that allows remote code execution on a production server is far more severe than one that leaks non-sensitive debug information.
  • Exploitability. How easy is it to exploit? Some vulnerabilities require physical access and specialized tools. Others can be exploited remotely with a single HTTP request.
  • Exposure. Is the vulnerable component internet-facing, internal-only, or in a test environment? The same vulnerability has vastly different risk profiles depending on where it exists.
  • Active exploitation. Is anyone actually exploiting this vulnerability in the wild? CISA's KEV catalog and EPSS scores help answer this question.

Why vulnerabilities matter for startups

According to IBM's 2025 Cost of a Data Breach report, the average cost of a data breach is $4.44 million globally, and most breaches begin with an exploited vulnerability or stolen credential. For startups, a single exploited vulnerability can mean lost customer trust, failed compliance audits, or the kind of security incident that derails a fundraise.

Here's the challenge:

  1. Volume is overwhelming. With 80+ new CVEs published daily, your team can't patch everything. The key is prioritization: using CVSS for severity, EPSS for exploitation probability, and KEV for confirmed active exploitation to focus on what actually matters.
  2. Vulnerabilities exist everywhere. They're in your application code (caught by SAST and DAST), your open-source dependencies (caught by SCA), your cloud configurations (caught by CSPM), and your external attack surface (caught by EASM). A mature vulnerability management program covers all these surfaces.
  3. Time-to-remediation is critical. The window between public vulnerability disclosure and active exploitation is shrinking. According to Mandiant, the average time-to-exploit for newly disclosed vulnerabilities has dropped to under a week for critical flaws. Startups need automated scanning and clear remediation SLAs to keep up.
  4. Compliance requires it. SOC 2 and ISO 27001 both require a formal vulnerability management process: regular scanning, risk-based prioritization, documented remediation timelines, and evidence of continuous improvement.

How Fencer helps with vulnerability management

Fencer provides a unified view of vulnerabilities across your code, cloud, and external attack surface. Rather than juggling separate SAST, SCA, CSPM, and EASM tools, Fencer consolidates findings into a single prioritized queue that accounts for CVSS severity, EPSS exploitation probability, KEV status, and the specific context of your environment. The result: your team sees the 10 vulnerabilities that matter this week, not the 500 that technically exist.