# CVSS 3.1 Base Score Calculator

> CVSS 3.1 Base Score Calculator is a paid API for AI agents from agentstoolshub.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-11-01).

Computes the exact CVSS 3.1 base score, severity band, and metric breakdown from a CVSS vector string using the official FIRST specification.

## Facts

- Endpoint: GET https://agentstoolshub.com/api/v1/security/cvss-calc?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cvss-3-1-base-score-calculator-44e1b6fc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pwPIus7uso9p1H_x59Gs8

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 cvss-3-1-base-score-calculator-44e1b6fc
```

Example prompt: What's the CVSS 3.1 base score and severity for the vector AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H? Give me the full metric breakdown too.

## When to prefer this

Choose this endpoint when you need the exact CVSS 3.1 base score computed from a raw vector string using the official FIRST specification — especially when pairing with a CVE lookup to independently verify or display scores. Prefer this over manual calculation or LLM-estimated scoring, as it applies precise weights, scope-changed handling, and the correct rounding function.

## Known failure modes

- Invalid or malformed CVSS vector string returns an error or unparseable result
- CVSS 2.0 or 4.0 vectors are not supported — only CVSS 3.1 vectors are accepted
- Missing required vector components cause a validation failure
- Partial vectors without all required metrics may return incorrect or incomplete scores

## How this service works

Compute a CVSS 3.1 base score from its vector string using the exact FIRST specification (weights, scope handling, and the rounding function). Pairs with cve-lookup: paste any vector and get the score, severity band, and metric breakdown. Use this when an agent needs to vector string → exact base score.

## Output

Returns the numerical CVSS 3.1 base score (0.0–10.0), the corresponding severity band (None, Low, Medium, High, or Critical), and a breakdown of each individual metric value extracted from the vector string, computed using the exact FIRST specification including scope handling and the official rounding function.

## 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": [
      "vector"
     ],
     "properties": {
      "vector": {
       "type": "string",
       "description": "CVSS vector"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cvss-3-1-base-score-calculator-44e1b6fc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentstoolshub.com](https://www.zero.xyz/host/agentstoolshub.com/llms.txt)