proxy_request · Vulnerable MCP Server MCP: Risk & Policy

WHAT IT DOES

What proxy_request does on Vulnerable MCP Server

AI agents invoke proxy_request to trigger actions in Vulnerable MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why proxy_request needs a policy

The name 'proxy_request' strongly implies this tool forwards or proxies HTTP/network requests to external or internal targets, which constitutes an external operation (SSRF risk, internal network pivoting). On a deliberately insecure server alongside tools like 'execute_system_command', 'fetch_url', and 'run_code', this tool likely enables server-side request forgery or lateral movement.

From the tool's definition Tool name 'proxy_request' on a deliberately insecure pentest MCP server; description is empty/uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

proxy_request Rate-limited

proxy_request stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "proxy_request": {
      "limits": [
        {
          "counter": "proxy_request_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Vulnerable MCP Server, so you can run agents against it safely.

FAQ

Questions about proxy_request

What does the proxy_request tool do? +

proxy_request. It is categorised as a Execute tool in the Vulnerable MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on proxy_request? +

Register the Vulnerable MCP Server MCP server in PolicyLayer and add a rule for proxy_request: 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 Vulnerable MCP Server. Nothing to install.

What risk level is proxy_request? +

proxy_request is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit proxy_request? +

Yes. Add a rate_limit block to the proxy_request 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 proxy_request completely? +

Set action: deny in the PolicyLayer policy for proxy_request. 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 proxy_request? +

proxy_request is provided by the Vulnerable MCP Server MCP server (joyghoshs/vulnerable-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.