# EPSS Exploit Score Lookup

> EPSS Exploit Score Lookup is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).

Returns the FIRST EPSS probability score, percentile, and scoring date for a given CVE, estimating the likelihood of exploitation in the next 30 days.

## Facts

- Endpoint: GET https://api.webintel-api.workers.dev/api/security/epss-exploit-score?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/epss-exploit-score-lookup-c7ca92d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5ghUrHLK1pdQRqa_jdp2i

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability epss-exploit-score-lookup-c7ca92d6
```

Example prompt: What's the EPSS exploitation probability score and percentile for CVE-2021-44228 — I want to know how likely it is to be actively exploited in the next 30 days?

## When to prefer this

Use this endpoint when you need a probabilistic, forward-looking exploitation likelihood score from FIRST's EPSS model for a specific CVE. Prefer this over CISA Known Exploits when you want a predicted risk score rather than confirmation of active exploitation. Ideal for prioritizing patch queues and enriching vulnerability reports with exploitation probability data.

## Known failure modes

- CVE ID not found in EPSS database — returns scored: false
- Malformed CVE ID format causes query failure
- FIRST upstream API unavailable or rate-limited
- CVE is too new to have an EPSS score yet
- Network timeout to upstream FIRST API

## How this service works

EPSS (Exploit Prediction Scoring System) for one CVE from FIRST's public API: the estimated probability (0 to 1) of exploitation in the next 30 days, its percentile among all scored CVEs and the scoring date. EPSS predicts; it does not say an exploit exists (see cisa-known-exploits).

## Output

Returns a JSON object containing the CVE ID, EPSS probability score (0 to 1 representing likelihood of exploitation in the next 30 days), the CVE's percentile rank among all EPSS-scored CVEs, the date the score was calculated, a boolean indicating whether the CVE was scored, a link to the source FIRST API response, and the timestamp when the check was performed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "cveId"
     ],
     "properties": {
      "cveId": {
       "type": "string",
       "description": "CVE identifier such as CVE-2021-44228 (required)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "date": "2026-10-22",
  "epss": 0.99999,
  "cveId": "CVE-2021-44228",
  "scored": true,
  "source": "https://api.first.org/data/v1/epss?cve=CVE-2021-44228",
  "checkedAt": "2026-10-23T09:38:39.115Z",
  "percentile": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/epss-exploit-score-lookup-c7ca92d6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.webintel-api.workers.dev](https://www.zero.xyz/host/api.webintel-api.workers.dev/llms.txt)