API Docs — NullCVE

Overview

The NullCVE REST API gives you programmatic access to the full vulnerability dataset — CVSS scores, EPSS probabilities, CISA KEV status, PoC availability, and the composite NullScore on every record.

API access is included in the Pro plan at $29/month. Upgrade to Pro to get your API key.

Pro

API access requires a Pro subscription. Get started — $29/month, cancel anytime. Full NullScore data on every record, filterable by severity, KEV status, EPSS threshold, and stack.

Authentication

All API requests require your API key passed as a Bearer token in the Authorization header.

# Example request with authentication
curl https://api.nullcve.io/v1/vulnerabilities \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json"

Keep your API key secret. Do not expose it in client-side code or public repositories. Rotate it immediately if compromised — contact API Docs hello@nullcve.io.

Base URL

https://api.nullcve.io/v1

All endpoints are versioned. The current version is v1. We will provide deprecation notices before breaking changes.

Endpoints Coming soon

The API is currently in development. These are the planned endpoints for the initial release. Sign up for Pro to be notified when access opens.

List vulnerabilities

GET /vulnerabilities Returns paginated list sorted by NullScore

Query parameters:

Parameter	Type	Description
limit optional	integer	Results per page. Default 50, max 500.
offset optional	integer	Pagination offset. Default 0.
severity optional	string	Filter by severity: critical, high, medium, low
kev optional	boolean	Filter to CISA KEV confirmed only
poc optional	boolean	Filter to CVEs with public PoC only
epss_min optional	float	Minimum EPSS score (0.0 to 1.0)
days optional	integer	Published within last N days. Default 30.

# Get critical KEV-confirmed CVEs from last 7 days
curl "https://api.nullcve.io/v1/vulnerabilities?severity=critical&kev=true&days=7" \
  -H "Authorization: Bearer YOUR_API_KEY"

// Response
{
  "data": [
    {
      "cve_id":       "CVE-2025-21298",
      "null_score":  98,
      "severity":    "CRITICAL",
      "cvss":        9.8,
      "epss":        0.97,
      "is_kev":      true,
      "poc_available": true,
      "description": "Windows OLE Remote Code Execution...",
      "action":      "Patch in 24 hours",
      "published":   "2025-01-14"
    }
  ],
  "total":  47,
  "limit":  50,
  "offset": 0
}

Get CVE by ID

GET /vulnerabilities/{cve_id} Full record for a specific CVE

curl "https://api.nullcve.io/v1/vulnerabilities/CVE-2025-21298" \
  -H "Authorization: Bearer YOUR_API_KEY"

KEV feed

GET /kev CISA Known Exploited Vulnerabilities with NullScore

Returns all CVEs currently on the CISA KEV catalog, enriched with NullScore and EPSS data, sorted by NullScore descending.

curl "https://api.nullcve.io/v1/kev" \
  -H "Authorization: Bearer YOUR_API_KEY"

Stack filter

POST /vulnerabilities/stack CVEs filtered to your tech stack

Returns CVEs matching your submitted tech stack components. Useful for automated recon and patch prioritization pipelines.

curl "https://api.nullcve.io/v1/vulnerabilities/stack" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "components": [
      {"name": "nginx", "version": "1.18"},
      {"name": "openssl", "version": "3.1"},
      {"name": "windows_server", "version": "2022"}
    ],
    "limit": 20
  }'

NullScore fields

Field	Type	Description
`null_score`	integer	Composite risk score 0–100. Higher = patch sooner.
`cvss`	float	CVSS v3.1 base score from NVD.
`epss`	float	EPSS exploitation probability 0.0–1.0 from First.org.
`is_kev`	boolean	True if confirmed on CISA KEV catalog.
`poc_available`	boolean	True if public PoC exploit code exists.
`severity`	string	CRITICAL, HIGH, MEDIUM, or LOW.
`action`	string	Plain English recommended action.

Error codes

Code	Meaning
`401`	Unauthorized — invalid or missing API key
`403`	Forbidden — feature not available on your plan
`404`	CVE ID not found in database
`429`	Rate limit exceeded — slow down requests
`500`	Server error — contact support if persistent

Rate limits

Plan	Requests per minute	Requests per day
Pro	60	10,000
Enterprise	Custom	Custom

Rate limit headers are included in every response: X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset.

Need higher limits? Contact us about Enterprise.

API Documentation