update_acl · ServiceNow- MCP: Risk & Policy

WHAT IT DOES

What update_acl does on ServiceNow-MCP

AI agents use update_acl to create or update resources in ServiceNow-MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your ServiceNow-MCP environment.

WHY IT NEEDS A POLICY

Why update_acl needs a policy

ACL (Access Control List) updates are reversible write operations that modify data—specifically security permissions and access rules. While this is a Write action (not Destructive, since ACL changes can be reverted), the severity is high because misuse could grant unauthorized access to sensitive ServiceNow data, escalate privileges, or compromise system security.

From the tool's definition Tool name 'update_acl' and description 'Update an existing ACL rule' indicates modification of access control lists, which are security-critical configurations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_acl Rate-limited

update_acl 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": {
    "update_acl": {
      "limits": [
        {
          "counter": "update_acl_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 ServiceNow-MCP, so you can run agents against it safely.

FAQ

Questions about update_acl

What does the update_acl tool do? +

Update an existing ACL rule (requires SCRIPTING_ENABLED=true). It is categorised as a Write tool in the ServiceNow-MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_acl? +

Register the ServiceNow- MCP server in PolicyLayer and add a rule for update_acl: 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 ServiceNow-MCP. Nothing to install.

What risk level is update_acl? +

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

Can I rate-limit update_acl? +

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

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

update_acl is provided by the ServiceNow- MCP server (tedorigawa001/servicenow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.