| name | implementing-epss-score-for-vulnerability-prioritization |
| description | Integrate FIRST's Exploit Prediction Scoring System (EPSS) API to prioritize vulnerability remediation based on real-world exploitation probability within 30 days. |
| domain | cybersecurity |
| subdomain | vulnerability-management |
| tags | ["epss","vulnerability-prioritization","first","exploit-prediction","cvss","risk-based","machine-learning"] |
| version | 1.0 |
| author | mahipal |
| license | Apache-2.0 |
| nist_csf | ["ID.RA-01","ID.RA-02","ID.IM-02","ID.RA-06"] |
Implementing EPSS Score for Vulnerability Prioritization
Overview
The Exploit Prediction Scoring System (EPSS) is a data-driven model developed by FIRST (Forum of Incident Response and Security Teams) that estimates the probability of a CVE being exploited in the wild within the next 30 days. EPSS produces scores from 0.0 to 1.0 (0% to 100%) using machine learning trained on real-world exploitation data. Unlike CVSS which measures severity, EPSS measures likelihood of exploitation, making it essential for risk-based vulnerability prioritization.
When to Use
- When deploying or configuring implementing epss score for vulnerability prioritization capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Common Misconfigurations & Verification
- Stale EPSS data — scores change daily. Verify the pipeline refreshes EPSS before each prioritization run.
- EPSS used alone — it predicts likelihood, not severity/impact. Verify it's combined with CVSS and asset context per the matrix.
- Percentile vs probability confusion — verify thresholds use the right field (
epss vs percentile).
- Missing CVEs scored as 0 — unmapped findings get silently deprioritized. Verify CVEs absent from the feed are flagged for review, not treated as low.
- No spike detection — verify trend/time-series checks catch a CVE whose EPSS jumps (emerging exploitation).
- Batching limits — verify >100-CVE queries are chunked so no findings are dropped.
Prerequisites
- Python 3.9+ with
requests, pandas, matplotlib
- Access to FIRST EPSS API (https://api.first.org/data/v1/epss)
- Vulnerability scan results with CVE identifiers
- Optional: NVD API key for CVSS enrichment
EPSS API Usage
Query Single CVE
curl -s "https://api.first.org/data/v1/epss?cve=CVE-2024-3400" | python3 -m json.tool
