Shopper is a Headless e-commerce Admin Panel. Prior to 2.8.0, CreateOrderFromCartAction::execute previously created the Order row before checking and incrementing the discount's total_use counter. Under concurrent checkout pressure (Black Friday, flash sale, viral coupon), the global usage_limit was silently exceeded: orders were committed with the discount fully applied to price_amount while the counter blocked at usage_limit. The merchant had no signal that an over-redemption had occurred. This vulnerability is fixed in 2.8.0.

Affected: Packagist: shopper/cart

## Impact

`CreateOrderFromCartAction::execute` previously created the `Order` row before checking and incrementing the discount's `total_use` counter. Under concurrent checkout pressure (Black Friday, flash sale, viral coupon), the global `usage_limit` was silently exceeded: orders were committed with the discount fully applied to `price_amount` while the counter blocked at `usage_limit`. The merchant had no signal that an over-redemption had occurred.

A second related bug: `usage_limit_per_user` was effectively a no-op because the counter it relied on (`DiscountDetail.total_use`) was never incremented anywhere in the codebase. The per-user check therefore always saw `0` uses and validation passed regardless of how many times the same customer had previously redeemed the coupon. For `eligibility = Everyone` the per-user limit could not fire at all because the underlying `DiscountDetail` row only exists for `eligibility = Customers`.

Direct financial loss: each over-redemption is a discount the merchant did not intend to grant.

## Patches

Fixed in `v2.8.0`. `CreateOrderFromCartAction` now:

- Reserves the discount slot atomically before the order row is created, inside the same `DB::transaction` with `lockForUpdate` and a compare-and-swap on `total_use`. - Throws `DiscountLimitReachedException::global` and rolls back the transaction when the global limit was exhausted between cart validation and commit. No order is committed. - Throws `DiscountLimitReachedException::perU…