To secure a Cursor + MongoDB + Railway stack, you need to: (1) store your MongoDB connection string in Railway environment variables (never in code), (2) validate all user input using libraries like Zod to prevent NoSQL injection, (3) implement application-level authorization checks on all protected routes since MongoDB lacks built-in RLS, (4) create a .cursorignore file to prevent AI from accessing your .env files, and (5) use an application-specific MongoDB user instead of admin credentials. This blueprint covers connection security, NoSQL injection prevention, and authorization patterns.
TL;DR
MongoDB on Railway requires careful connection string management and query security. Store your MongoDB connection string in Railway environment variables, never in code. Use parameterized queries to prevent NoSQL injection. Enable MongoDB authentication with strong passwords, and restrict network access when possible. Unlike RLS in Supabase, MongoDB relies on application-level authorization checks.
Platform Guides & Checklists
Cursor Security Guide
MongoDB Security Guide
Railway Security Guide
Pre-Launch Checklist
Stack Overview
This stack is popular for Node.js applications that need flexible document storage. Security responsibilities are distributed across the stack:
| Component | Role | Security Focus |
|---|---|---|
| Cursor | AI code editor | Query safety, secret detection |
| MongoDB | Document database | Authentication, query safety |
| Railway | Hosting platform | Environment variables, network isolation |
Part 1: Connection String Security MongoDB Railway
Your MongoDB connection string contains credentials. Never hardcode it:
// Exposed credentials in code
const client = new MongoClient(
'mongodb+srv://admin:password123@cluster.mongodb.net/myapp'
);
// Use environment variable
const client = new MongoClient(process.env.MONGODB_URI);
Part 2: Preventing NoSQL Injection MongoDB Cursor
The Risk in AI-Generated Code Cursor
Cursor might generate code that directly uses user input in queries:
// DANGEROUS: User input directly in query
app.get('/user', async (req, res) => {
const user = await db.collection('users').findOne({
username: req.query.username // Could be an object!
});
res.json(user);
});
// Attacker sends: ?username[$ne]=null
// This returns the first user in the database!
Safe Query Patterns MongoDB
import { z } from 'zod';
// Validate and sanitize input
const usernameSchema = z.string().min(1).max(50);
app.get('/user', async (req, res) => {
// Validate input type
const result = usernameSchema.safeParse(req.query.username);
if (!result.success) {
return res.status(400).json({ error: 'Invalid username' });
}
// Now safe to query
const user = await db.collection('users').findOne({
username: result.data // Guaranteed to be a string
});
if (!user) {
return res.status(404).json({ error: 'User not found' });
}
// Don't return sensitive fields
const { password, ...safeUser } = user;
res.json(safeUser);
});
Part 3: Application-Level Authorization MongoDB
Unlike Supabase RLS, MongoDB relies on your application code for authorization:
// Middleware to check resource ownership
async function checkOwnership(req, res, next) {
const resource = await db.collection('posts').findOne({
_id: new ObjectId(req.params.id)
});
if (!resource) {
return res.status(404).json({ error: 'Not found' });
}
if (resource.userId.toString() !== req.user.id) {
return res.status(403).json({ error: 'Forbidden' });
}
req.resource = resource;
next();
}
// Use in routes
app.put('/posts/:id', authenticate, checkOwnership, async (req, res) => {
await db.collection('posts').updateOne(
{ _id: new ObjectId(req.params.id) },
{ $set: { title: req.body.title, content: req.body.content } }
);
res.json({ success: true });
});
Security Checklist
Pre-Launch Checklist for Cursor + MongoDB + Railway
MongoDB connection string in Railway env vars
No credentials in code or git
Application-specific MongoDB user (not admin)
Input validation on all query parameters
Authorization checks on protected routes
$where operator disabled or input sanitized
Error messages don't expose database details
.cursorignore excludes .env files
MongoDB network access restricted appropriately
Alternative Stack Configurations
Cursor + Supabase + Vercel Swap MongoDB for PostgreSQL with built-in RLS. Different security model, no NoSQL injection concerns.
Cursor + Neon + Railway
Same Railway hosting, but with serverless Postgres. RLS support and SQL injection patterns.
MERN Stack Security
Full MERN stack guide with React frontend and Express backend patterns.
Is MongoDB less secure than SQL databases?
Not inherently. MongoDB has different security patterns than SQL databases. The main difference is NoSQL injection vs SQL injection, both preventable with proper input validation. MongoDB's flexibility means you need more application-level authorization.
Should I use Mongoose or the native driver?
Mongoose provides schema validation which helps prevent injection attacks. The native driver is faster but requires more manual validation. For security, Mongoose's built-in type checking is helpful, especially with AI-generated code.