rolefence-scan

Find out what your AI assistant can really see in your database, before someone else does.

Part of RoleFence. Free and open source (Apache 2.0). Made by VTSOL INC.

What is it?

Many companies now let an AI assistant (Claude, ChatGPT, Codex and others) answer questions from the company database. The AI talks to the database through an "MCP server": a small program that holds a list of questions the AI may ask.

The problem: these setups are new, done by hand, and easy to get slightly wrong. A tool meant to answer "how many enquiries did we get in June?" can often also read every customer's phone number, see the supplier costs that sales staff should never see, or even change data.

rolefence-scan is a checker. You point it at the address your AI uses, and it tells you, in plain English:

• what it saw (for example: "the server lists 6 tools to anyone, with no login")
• why it matters (for example: "anyone on this address can ask those questions, and nobody is recorded as having asked")
• how to close it (for example: "put a login in front; here is which setting")

It only reads. It never changes anything in the database or the server it checks.

What is the goal?

Before you give an AI access to company data, you want three things to be true:

1. The AI can only read, never write.
2. Each role (sales, finance, support, …) can reach only its own data, and the hidden fields really stay hidden.
3. There is a login, so you know who asked what.

rolefence-scan checks whether that is true today, so you can fix the gaps. Run it again after every change, or in your deployment pipeline, so a mistake never reaches production without a warning.

How do I use it?

1. Install

You need Python 3.11 or newer.

uvx rolefence-scan --help

(or pipx install rolefence-scan)

2. The easy way: the wizard in your browser

rolefence-scan ui

This opens a page on your own computer (http://127.0.0.1:8765, reachable only from this machine) that walks you through five short steps: the server address, an optional login token, an optional database login (server, database name, username, password, with a "Test login" button), an optional config file, then a review and the run. Each check appears as it finishes; the findings are shown as cards you can download as an HTML or JSON report. Tokens and connection strings are kept in memory for that one run and never saved.

Not sure where to find the address, the connection string or the config file? Each step has a "Where do I find it?" link. In short: the address is in your AI app's MCP settings (for Claude Code, .mcp.json; for Claude Desktop, Settings → Developer → Edit Config); the config file (tools.yaml) and the connection string live on the machine where the MCP server runs, so ask whoever set it up. Everything but the address is optional.

2b. Or the command line

The simplest run: just the address your AI assistant is configured with.

rolefence-scan --mcp http://127.0.0.1:5000/mcp

That already tells you whether the server answers without a login, whether a "sales" address leaks the "finance" tools, and whether the server is open to the whole office network.

3. Give it more, get more

Each extra piece of information unlocks more checks. Passwords and tokens are never typed on the command line: you put them in an environment variable and give the scanner the variable's name.

Add this	And the scanner can also check
--token-env SALES_TOKEN --role sales (a login token for one role)	Is the token accepted? Does the sales role see tools it is not allowed to call?
--backend http://… (the server's own address behind the gateway)	Can someone skip the gateway and call the server directly?
--db-env DB_URI (the database connection the server uses)	Can the AI's database user write? Can it run code inside the database? Can one tool read other collections?
--config tools.yaml (the server's config file)	Are there write tools? Do tools accept any query? Do they return whole records, or unlimited rows?

A full run looks like this:

export SALES_TOKEN='...'                                   # a login token for the sales role
export DB_URI='mongodb://user:pw@host/db?authSource=db'   # the connection the MCP server uses

rolefence-scan --mcp http://127.0.0.1:3001/mcp --token-env SALES_TOKEN --role sales \
               --backend http://127.0.0.1:5002/mcp \
               --db-env DB_URI --config tools.yaml --json report.json

The exit code tells a script how it went: 0 nothing found, 1 low or medium findings, 2 at least one high finding, 3 it could not run. Use it in CI to stop a deploy that opens something up.

4. Or just ask your AI assistant to run it

The scanner can itself be an MCP server. Register it with Claude Code, Codex or any MCP client, and ask in plain words: "scan my MCP server at http://127.0.0.1:3001/mcp as the sales role". The assistant runs the checks and explains the report.

{"mcpServers": {"rolefence-scan": {"command": "rolefence-scan", "args": ["serve"]}}}

Set the environment variables in the shell that starts the assistant. The assistant only ever sees variable names, never the secrets.

What does a report look like?

This is a real run against the "weak" demo setup that ships with the scanner (made-up data):

rolefence-scan report for http://127.0.0.1:5010/mcp/sales

11 finding(s): 6 high, 3 medium, 2 low

1. [HIGH] Tools are listed without a login
   What we saw:    The server answered with 3 tool(s) when no token was sent.
   Why it matters: Anyone who can reach this address can see every question the AI can ask
                   and call them. There is no record of who asked.
   How to close:   Put a login in front: a gateway that checks tokens, or the question
                   server's own auth setting.

2. [HIGH] The bare /mcp address serves every tool
   What we saw:    /mcp/sales lists 3 tool(s); /mcp lists 6, including 3 not meant for this caller.
   Why it matters: Per-role toolsets are a menu, not a boundary. Anyone who drops the toolset
                   name from the address gets everything.

3. [HIGH] The AI's database user can write
   What we saw:    The user the question server connects with holds write rights.
   Why it matters: A tool mistake, a prompt injection, or a pipeline with $out/$merge can
                   change or delete data.
   How to close:   Create a user with a custom read-only role and point the server at it.

4. [HIGH] Server-side JavaScript runs for the AI's database user
   ...

The same company, set up properly (one read-only user per role, fixed questions, a login in front), gets 4 findings instead of 11, and the scanner says which ones remain.

Examples

"Our sales team's AI must never see supplier cost." Run with --db-env set to the sales user's connection. If the scanner reports "cross-collection reach" into orders or "the AI's database user can write", the database user is too powerful, whatever the tools say. If it reports "Cross-collection reach is contained by the database role", the data layer is doing its job.

"We put a gateway with login in front. Are we done?" Run with --mcp on the gateway and --backend on the server behind it. "The question server can be reached without the gateway" means anyone who knows the inside address skips the login.

"Users say they get 401 even with a valid login." Run with --token-env. "A valid token is refused" with the hint about pass-through means the gateway checked the token and then threw it away before forwarding, so the server behind it saw none. One setting fixes it.

"A developer set this up months ago. Is it still safe?" Run it with everything you have, save --json report.json, and run it again after each change. Compare the two.

The full list of checks

Check	Needs	What it looks for
Open tool list	--mcp	The server lists and serves tools with no login
Default /mcp toolset	--mcp .../mcp/<role>	The bare /mcp address serves every tool
Scopes advertised	--mcp (login on)	Clients are told which scopes to ask for
Listening everywhere	--mcp on localhost	The port is also open on the machine's network address
Token refused	--mcp --token-env	A valid token gets 401 (a gateway in front may be dropping it)
Tool list not filtered	--mcp --token-env	The caller sees tools it may not call
Round the gateway	--backend	The question server answers directly, with no token
Writes allowed	--db-env	The AI's database user holds write rights (read from its privileges; no write is tried)
Server-side JavaScript	--db-env	$function / $where run
Cross-collection reach	--db-env	$lookup from a tool's collection pulls rows from others
Leaks in replies	--db-env	$collStats returns the host name; errors echo the full query
Write tools	--config	Insert, update or delete tools are defined
Free-form queries	--config	Tools take the whole filter or pipeline from the model
Aggregate not read-only	--config	mongodb-aggregate without readOnly: true
No row cap	--config	Fixed pipelines with no $limit
Whole documents	--config	Find tools with no projection

Works today with MongoDB and MCP Toolbox for Databases, with or without agentgateway in front. Other databases are planned.

Try it on the demo

demo/ holds a made-up removals company, Brightline Movers: 2,000 customers, 3,200 enquiries, 1,110 orders, all invented. It comes with two setups:

• demo/toolbox/weak.yaml: how a first attempt usually looks. One over-powered database user, tools that accept any query, no login. Expected: 11 findings.
• demo/toolbox/governed.yaml: fixed questions, one read-only user per role, hidden fields removed by a view. Expected: 4 findings, all about the missing login (that is the gateway's job, below) and a database setting.

export DEMO_ADMIN_URI='mongodb://<admin>:<pw>@127.0.0.1:27017/admin'
uv run python demo/seed.py                    # writes database rolefence_demo
mongosh ... demo/setup_users.js               # see the header of that file for the command
toolbox --config demo/toolbox/weak.yaml --port 5010     # with DEMO_RW_URI set
rolefence-scan --mcp http://127.0.0.1:5010/mcp/sales --db-env DEMO_RW_URI --config demo/toolbox/weak.yaml

With a login and a gateway

demo/gateway/ adds the identity side: a Keycloak realm (rolefence-demo, roles sales and finance, scopes demo:sales / demo:finance), a third Toolbox config with Toolbox's own login (demo/toolbox/governed_auth.yaml, port 5012), and two agentgateway configs in front of it: gateway_good.yaml (port 3011, passes the token on) and gateway_weak.yaml (port 3012, drops it, which is agentgateway's default). Passwords are typed into the terminal, never written to a file; get_token.sh fetches a token into a variable and prints only who it is for.

# 1. Keycloak (Docker) and the demo realm
docker run -d --name keycloak -p 127.0.0.1:8080:8080 -e KC_BOOTSTRAP_ADMIN_USERNAME=admin \
  -e KC_BOOTSTRAP_ADMIN_PASSWORD="$KC_ADMIN_PW" quay.io/keycloak/keycloak:26.7.1 start-dev
export KC_ADMIN_PW DEMO_SALES_USER_PW DEMO_FINANCE_USER_PW   # typed with read -s, see the script header
demo/gateway/setup_keycloak.sh

# 2. Toolbox with its own login (needs DEMO_SALES_URI / DEMO_FINANCE_URI as for governed.yaml)
toolbox --config demo/toolbox/governed_auth.yaml --port 5012

# 3. The two gateways (binary from https://github.com/agentgateway/agentgateway/releases)
agentgateway -f demo/gateway/gateway_good.yaml &
agentgateway -f demo/gateway/gateway_weak.yaml &

# 4. A sales token, then scan
source demo/gateway/get_token.sh sales                        # sets DEMO_SALES_TOKEN
rolefence-scan --mcp http://127.0.0.1:3011/mcp --token-env DEMO_SALES_TOKEN --role sales \
               --backend http://127.0.0.1:5012/mcp --config demo/toolbox/governed_auth.yaml
rolefence-scan --mcp http://127.0.0.1:3012/mcp --token-env DEMO_SALES_TOKEN --role sales \
               --backend http://127.0.0.1:5011/mcp
rolefence-scan --mcp http://127.0.0.1:5012/mcp --token-env DEMO_SALES_TOKEN --role sales

What each run shows:

Target	Expected
Good gateway (3011)	Token accepted, sales sees only sales_* tools, scopes advertised, backend 5012 refuses direct calls. Only "listening everywhere" remains (the gateway has no bind setting).
Weak gateway (3012)	Token refused: the gateway checks the token, then drops it, so Toolbox answers 401. Scopes not advertised. With the open governed Toolbox (5011) as backend: round the gateway.
Toolbox alone (5012)	Login holds, but the tool list is not filtered: sales is shown the finance tools and refused when it calls them. No resource metadata.

What it does not do yet

• Secrets that can be worked out from other fields. If sales can see price and the AI can find cost somewhere, it can work out the margin. The scanner cannot know which fields are secret in your business. Planned: a short wizard where you tick the secret fields and the scanner checks each role against them.
• Watching the server over time, for example telling you that a config change was rejected and the old config is still running.
• Fixing things. It finds and explains; you (or the RoleFence console) make the change.
• PostgreSQL and other databases. MongoDB first.

Is it safe to run on a live system?

Yes, by design:

• It only reads: it asks the database what the user is allowed to do, runs tiny read queries, and calls tools with empty arguments. Nothing is inserted, updated or deleted.
• The report never contains data values, only names of fields, collections and tools, and counts.
• Secrets are never on the command line, so they do not end up in shell history or logs.
• reports/ and *.report.json are git-ignored, because a report can contain host names.

Questions or ideas

Open an issue. If you found a gap the scanner missed, that is the most useful thing you can tell us: every new check started as someone's "it shouldn't have been able to do that".