cmux_session_recover

THE RISK

High Risk

Why cmux_session_recover needs a policy

This tool recreates and resumes multiple CLI sessions and workspaces, triggering external operations (spawning processes, resuming CLI agents) whose effects depend on the saved manifest state. It is not merely reading data — it actively executes and orchestrates multiple CLI sessions. The blast radius is high because misuse could resume unintended or malicious CLI processes across multiple parallel sessions.

From the tool's definition Recover a crashed CMUX session from the saved manifest. Recreates all workspaces, panes, and RESUMES each CLI

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

POLICY

How to control cmux_session_recover

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

policy.json

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

cmux_session_recover 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 Cmux Agent — 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 Cmux Agent tools

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Go deeper

High-risk tools in Cmux Agent → 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 →

FAQ

Questions about cmux_session_recover

What does the cmux_session_recover tool do? +

Recover a crashed CMUX session from the saved manifest. Recreates all workspaces, panes, and RESUMES each CLI. It is categorised as a Execute tool in the Cmux Agent MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on cmux_session_recover? +

Register the Cmux Agent MCP server in PolicyLayer and add a rule for cmux_session_recover: 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 Cmux Agent. Nothing to install.

What risk level is cmux_session_recover? +

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

Can I rate-limit cmux_session_recover? +

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

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

cmux_session_recover is provided by the Cmux Agent MCP server (multiagentcognition/cmux-agent-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Cmux Agent tool call.

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

CHECK YOUR STACK →