rbac_add_user · n8n Workflow Builder MCP: Risk & Policy

WHAT IT DOES

What rbac_add_user does on n8n Workflow Builder

AI agents use rbac_add_user to create or update resources in n8n Workflow Builder — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your n8n Workflow Builder environment.

WHY IT NEEDS A POLICY

Why rbac_add_user needs a policy

This tool creates new user accounts and assigns roles within n8n, which is a Write operation as it creates records that can theoretically be undone (user deletion). Severity is high because unauthorized user creation with elevated roles could grant attackers persistent access to workflow systems, expose sensitive data workflows, or allow execution of arbitrary operations within n8n.

From the tool's definition Tool name 'rbac_add_user' and description 'Add a new user with specific role and tenant' indicates creation of a new user account with role assignment in an n8n system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rbac_add_user Rate-limited

rbac_add_user stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "rbac_add_user": {
      "limits": [
        {
          "counter": "rbac_add_user_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches n8n Workflow Builder, so you can run agents against it safely.

FAQ

Questions about rbac_add_user

What does the rbac_add_user tool do? +

👤 Add a new user with specific role and tenant. It is categorised as a Write tool in the n8n Workflow Builder MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on rbac_add_user? +

Register the n8n Workflow Builder MCP server in PolicyLayer and add a rule for rbac_add_user: 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 n8n Workflow Builder. Nothing to install.

What risk level is rbac_add_user? +

rbac_add_user is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit rbac_add_user? +

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

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

rbac_add_user is provided by the n8n Workflow Builder MCP server (schimmilab/n8n-workflow-builder). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.