Scoring Methodology

The CNA Scorecard promotes transparency and accountability in vulnerability reporting by measuring how completely CVE Numbering Authorities populate essential data fields. The scoring philosophy is simple: complete, actionable vulnerability data leads to better security outcomes for everyone.

Scoring Window

Current Analysis Period

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All CNA scores are based on CVE records published during this 6-month window. This ensures scores reflect recent performance and current data quality practices.

How the Scoring Window Works

  • Rolling 6-Month Window: The analysis period automatically updates to always cover the most recent 6 months of CVE data.
  • Fresh Data: Scores are recalculated regularly using only CVEs published within the current window, ensuring relevance and accuracy.
  • Trend Analysis: Performance trends compare the current 6-month period against the previous 6-month period to show improvement or decline.
  • Fair Comparison: All CNAs are evaluated using the same time window, creating consistent and comparable scoring across organizations.

Scoring Categories

The scoring system evaluates CVE records across five essential categories, with points allocated based on the relative importance of each type of information for security decision-making.

50 points Foundational Completeness

What it is: The essential building blocks of every CVE record, including problem types, affected products, references, and descriptions.

Why it matters: These are the minimum fields required for CVE publication and provide the basic context needed to understand any vulnerability. Without complete foundational data, security teams cannot properly identify or assess threats.

How points are awarded: Points are earned for including comprehensive problem type classifications, detailed affected product information, relevant reference links, and clear vulnerability descriptions.

15 points Root Cause Analysis

What it is: Information about the underlying weakness that caused the vulnerability, typically expressed as a CWE (Common Weakness Enumeration) identifier.

Why it matters: CWE data helps development teams understand patterns in security flaws and implement preventive measures. It's like knowing that a house fire was caused by faulty wiring versus a gas leak—the root cause determines the best prevention strategy.

How points are awarded: Points are earned for including valid CWE identifiers that accurately describe the specific type of weakness, rather than generic classifications.

15 points Severity & Impact Context

What it is: Standardized severity ratings using CVSS (Common Vulnerability Scoring System) metrics, which provide numerical scores from 0-10 indicating how serious a vulnerability is.

Why it matters: CVSS scores help organizations prioritize which vulnerabilities to fix first based on potential impact. A CVSS score of 9.8 demands immediate attention, while a 3.1 might be scheduled for routine patching.

How points are awarded: Points are earned for including complete CVSS v3 or v4 metrics with valid vector strings that accurately reflect the vulnerability's exploitability and impact.

10 points Software Identification

What it is: Precise identification of affected software using CPE (Common Platform Enumeration) format, which provides standardized names for software products and versions.

Why it matters: CPE data enables automated vulnerability scanners to accurately match vulnerabilities to specific software in an organization's environment. Without it, security tools can't reliably identify what's at risk.

How points are awarded: Points are earned for including valid CPE identifiers that precisely specify the affected software products, versions, and configurations.

10 points Patch Information

What it is: Direct links to patches, fixes, or official vendor advisories that provide remediation guidance.

Why it matters: Patch information bridges the gap between identifying a vulnerability and actually fixing it. Security teams need clear paths to remediation, not just problem descriptions.

How points are awarded: Points are earned for including direct links to official patches or vendor advisories, rather than generic references or third-party discussions.

Technical Documentation for CNAs

This section provides the exact technical implementation details for CNAs who want to verify the scoring methodology. All field paths reference the official CVE JSON 5.0 schema.

Grading Tiers

Scores are calculated as a percentage of total possible points (100), then mapped to letter grades for easy interpretation:

Perfect 100% All essential data fields are complete and accurate
Great >75% Most critical information is provided with minor gaps
Good >50% Basic requirements met with room for improvement
Needs Work <50% Significant gaps in essential vulnerability data
Missing Data 0% No scoring data available for this CNA

Performance Trends Analysis

Beyond point-in-time scoring, the CNA Scorecard tracks performance trends over time using rolling 7-day averages to identify patterns and improvements in vulnerability data quality.

Rolling 7-Day Averages

What it tracks: Daily average scores for each scoring category calculated over sliding 7-day windows, updated daily for the past 6 months.

Why it matters: Smooths out daily fluctuations to reveal genuine trends in data quality improvement or decline. A single bad day doesn't define overall performance.

How it works: Each day's score represents the average of the previous 7 days, creating a smooth trend line that highlights meaningful patterns over noise.

Top Improving CNAs

What it identifies: CNAs showing the most significant improvement by comparing their earliest versus most recent 7-day performance averages over a 6-month analysis period.

Why it's valuable: Recognizes CNAs making genuine efforts to improve their vulnerability reporting practices and helps identify best practices worth emulating.

How it's calculated: Improvement score equals the difference between the most recent 7-day average and the earliest 7-day average for each CNA with sufficient data.

Trend Visualization

What it shows: Interactive line charts displaying rolling averages for Root Cause Analysis (CWE), Severity & Impact (CVSS), Software Identification (CPE), and Patch Information categories.

Why separate charts: Each scoring category has different typical ranges and improvement patterns, requiring dedicated visualization for meaningful analysis.

How it adapts: Charts use auto-scaling Y-axes that adjust to actual data ranges, ensuring trend visibility whether scores are high-performing or need improvement.

Transparency & Open Standards

The CNA Scorecard is committed to complete transparency in methodology. Every aspect of the scoring system is based on established industry standards and open specifications. The scoring logic is fully documented and publicly available, ensuring that CNAs and security professionals can understand exactly how scores are calculated.

All scoring algorithms, data processing methods, and evaluation criteria are open source and available for review in the project repository. Feedback and contributions from the security community are welcome to continuously improve the methodology.