bundle-exec

THE RISK

High Risk

Why bundle-exec needs a policy

This tool runs arbitrary commands within the Ruby Bundler environment. An AI agent could misuse it to execute any shell command available in the bundle context, making it a significant execution risk with high blast radius depending on what commands are passed.

From the tool's definition 'Executes a command in the context of the Gemfile bundle' — the word 'Executes' and the ability to run arbitrary commands via bundle exec

Documented attack patterns abuse exactly the kind of access bundle-exec gives an agent:

POLICY

How to control bundle-exec

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "bundle-exec": {
      "limits": [
        {
          "counter": "bundle-exec_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

bundle-exec 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.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Http tools

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All 202 Http tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

Govern code and CI agents → Branch allowlists, approval on merges, and rate caps on the build and pipeline tools agents trigger.
High-risk tools in Http → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about bundle-exec

What does the bundle-exec tool do? +

Executes a command in the context of the Gemfile bundle using. It is categorised as a Execute tool in the Http MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on bundle-exec? +

Register the Http MCP server in PolicyLayer and add a rule for bundle-exec: 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 Http. Nothing to install.

What risk level is bundle-exec? +

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

Can I rate-limit bundle-exec? +

Yes. Add a rate_limit block to the bundle-exec 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 bundle-exec completely? +

Set action: deny in the PolicyLayer policy for bundle-exec. 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 bundle-exec? +

bundle-exec is provided by the Http MCP server (@paretools/http). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Http tool call.

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

CHECK YOUR STACK →