check_kev

THE RISK

Low Risk

Why check_kev needs a policy

This tool retrieves and queries existing vulnerability intelligence data without modifying, deleting, or executing any operations. It is purely informational - checking whether a CVE identifier exists in a known exploited vulnerabilities catalog. The low severity reflects minimal blast radius if misused by an AI agent, as it only exposes read-only security information that is already public.

From the tool's definition Tool performs a lookup/query operation against the CISA KEV catalog to check if a CVE exists in that database.

Documented attack patterns abuse exactly the kind of access check_kev gives an agent:

POLICY

How to control check_kev

PolicyLayer is an MCP gateway — it sits between your AI agents and CVE MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for check_kev:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "check_kev": {}
  }
}

check_kev is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register CVE MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More CVE MCP Server tools

Read parse_cvss Parse and explain a CVSS vector string (v2, v3.x, or v4.0). Args: vector: CVS Read calculate_risk_score Calculate a composite 0-100 risk score using CVSS, EPSS, KEV, and PoC data. Read check_exploit_availability Search GitHub for public proof-of-concept (PoC) exploit repositories for a CVE. Result Read check_ip_reputation Check an IP address reputation via AbuseIPDB and GreyNoise Community. Returns abuse co Read check_package_vulns Check a package for known vulnerabilities via OSV.dev. Args: package: Package Read check_poc_exists Search for proof-of-concept exploits across GitHub, Exploit-DB, and Nuclei templates. Read check_ransomware_intel Check if a Bitcoin address is associated with a known ransomware family using the Rans Read check_url_safety Check a URL or domain for malicious activity via URLScan.io. Returns scan verdicts, ma

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about check_kev

What does the check_kev tool do? +

Check if a CVE is in the CISA Known Exploited Vulnerabilities (KEV) catalog. Args: cve_id: CVE identifier (e.g. CVE-2021-44228). It is categorised as a Read tool in the CVE MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on check_kev? +

Register the CVE MCP Server MCP server in PolicyLayer and add a rule for check_kev: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches CVE MCP Server. Nothing to install.

What risk level is check_kev? +

check_kev is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit check_kev? +

Yes. Add a rate_limit block to the check_kev rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block check_kev completely? +

Set action: deny in the PolicyLayer policy for check_kev. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides check_kev? +

check_kev is provided by the CVE MCP Server MCP server (mukul975/cve-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every CVE MCP Server tool call.

Start from CVE MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →