mcp-tenant-isolation

Static analysis scanner for multi-tenant SaaS and MCP server code. 57 deterministic rules that catch cross-tenant data leakage before it reaches production.

What it does

If you build multi-tenant software, every query, every cache key, every file access, every API response needs to be scoped to the right tenant. Miss one, and Tenant A sees Tenant B's data. That's not a bug you want to find in production.

This scanner reads your source code and checks whether tenant isolation guards are present where they need to be. It covers 57 patterns across database queries, API routes, cache keys, file storage, schema design, logging, and MCP server architecture. It works with TypeScript, JavaScript, Prisma, Drizzle, raw SQL, Next.js, Express, and Fastify.

The scanner also runs as an MCP server, so you can plug it into Claude Desktop, Cursor, or any MCP-compatible agent and have your AI assistant scan code on demand.

Who uses this

• SaaS engineering teams who need to catch tenant isolation gaps before code ships
• MCP server developers building tools that handle tenant-scoped data
• Security teams who want tenant isolation checks in CI/CD
• AI agent developers who want their agents to scan code for cross-tenant risks

Why this exists

General-purpose security scanners are not purpose-built for tenant isolation patterns. They catch SQL injection and XSS. They do not check whether your findMany query includes an organizationId filter. They do not check whether your MCP tool handler scopes tool visibility by tenant. They do not check whether your cache key includes a tenant prefix.

This scanner does exactly that. 57 rules, each checking for a specific tenant isolation pattern, each producing a finding with the rule ID, file, line, missing guard, and a remediation hint.

Every rule is deterministic. Given the same source code, the scanner produces the same findings. No machine learning, no probabilistic scoring. Static analysis has inherent limitations though. It cannot verify runtime behavior, database-level enforcement, or dynamic tenant isolation. The scan output includes a limitations field that lists what was and was not checked for each run.

Install

npm install -g mcp-tenant-isolation

# or use npx (no install needed)
npx mcp-tenant-isolation scan ./src

# or use Docker (no Node.js needed)
docker run --rm -v $(pwd):/code subodhkc/mcp-tenant-isolation scan /code/src

Requires Node.js 22 or later.

Quick start

mti scan ./src
mti scan ./src --format sarif --output results.sarif
mti scan ./src --format markdown --output TENANT-ISOLATION-REPORT.md
mti scan ./src --format ai --output findings.json
mti scan ./src --severity HIGH
mti rules                          # list all 57 rules
mti baseline                       # snapshot current findings for proof-of-fix tracking
mti init                           # create .mtirc.json with defaults

Demo

Rules

42 general multi-tenant rules

... View full README on GitHub