What an audit gives you

Impact

Full read of the orders table, including customer names, addresses and payment references, and a plausible path to writing or dropping data.

Exploit scenario

A request to `/orders/1 or 1=1` returns every order in the table. `/orders/1; drop table orders --` runs a second statement on a driver that allows it. No account is needed: the route is reachable before the session check on line 39.

Fix

Pass the identifier as a bound parameter and reject anything that is not a UUID before the query runs.

How to fix it

1. Validate the parameter: `if (!isUuid(req.params.id)) return res.status(400).json({ error: "Invalid order id." });`
2. Replace the concatenated query with a parameterized one, as in the patch below.
3. Search the rest of `src/routes` for the same pattern — `db.query("… " +` — and convert those too.
4. Add a regression test that requests `/orders/1 or 1=1` and expects 400.

Patch

const { rows } = await db.query(
  "select * from orders where id = $1",
  [req.params.id],
);

How to verify

Replay `GET /orders/1%20or%201=1`: it must answer 400, and the Postgres log must show the parameterized statement with the raw value bound, not interpolated.

References

• https://cwe.mitre.org/data/definitions/89.html
• https://owasp.org/Top10/A03_2021-Injection/

Impact

Cross-customer data exposure: addresses, totals and payment references belonging to other accounts.

Exploit scenario

A customer who signs up legitimately can iterate order identifiers and read other customers' orders. Nothing in the logs distinguishes this from normal use.

Fix

Scope the query to the session's user, so an identifier alone is never enough.

How to fix it

1. Add `and user_id = $2` to the query and pass `req.session.userId`.
2. Return 404 rather than 403 when the row is missing, so the endpoint does not confirm which identifiers exist.
3. Apply the same scoping to `PATCH /orders/:id` and `POST /orders/:id/refund`.

Patch

const { rows } = await db.query(
  "select * from orders where id = $1 and user_id = $2",
  [req.params.id, req.session.userId],
);
if (rows.length === 0) return res.status(404).end();

How to verify

Sign in as one account and request an order created by another: the response must be 404, and the row must not appear in the body.

References

• https://cwe.mitre.org/data/definitions/639.html

Impact

Full API access to the payment account, independent of this service.

Exploit scenario

The key is in every clone and in the commit history. It allows charges, refunds and customer reads against the live account until it is rotated.

Fix

Rotate the key first, then remove the fallback so a missing variable fails loudly at boot.

How to fix it

1. Roll the key in the Stripe dashboard now; the committed one must be treated as public.
2. Replace the fallback with a hard failure, as in the patch.
3. Purge the value from history (`git filter-repo`) or accept that the old key stays exposed and rely on the rotation.
4. Add a secret scan to CI so the next one is caught before it merges.

Patch

const key = process.env.STRIPE_SECRET_KEY;
if (!key) throw new Error("STRIPE_SECRET_KEY is not set");
export const STRIPE_KEY = key;

How to verify

Start the service without `STRIPE_SECRET_KEY`: it must refuse to boot instead of using a built-in value.

References

• https://cwe.mitre.org/data/definitions/798.html

Impact

Double refunds and a bill at the payment provider for traffic nobody asked for.

Exploit scenario

A customer sending the same refund twice within a few milliseconds can have the order refunded twice before the status is written back.

Fix

Limit the endpoint per account and make the refund idempotent at the database level.

How to fix it

1. Add a limiter keyed on the session's user, e.g. 5 refunds per hour.
2. Claim the refund with a conditional update — `update orders set status = 'refunding' where id = $1 and status = 'paid' returning id` — and only call Stripe when a row comes back.
3. Pass an idempotency key to the Stripe call so a retry cannot charge twice.

How to verify

Fire two refund requests for the same order in parallel: exactly one must reach Stripe, and the second must answer 409.

References

• https://cwe.mitre.org/data/definitions/770.html