{"id":"CVE-2026-47741","aliases":["GHSA-9rh9-hf3w-9fgg"],"url":"https://o3.security/vulnerability/CVE-2026-47741","summary":"Shopper: Race condition on Discount.usage_limit allows silent over-redemption","details":"## Impact\n\n`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.\n\nA 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`.\n\nDirect financial loss: each over-redemption is a discount the merchant did not intend to grant.\n\n## Patches\n\nFixed in `v2.8.0`. `CreateOrderFromCartAction` now:\n\n- 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`.\n- Throws `DiscountLimitReachedException::global` and rolls back the transaction when the global limit was exhausted between cart validation and commit. No order is committed.\n- Throws `DiscountLimitReachedException::perUser` and rolls back when the discount is restricted to one use per customer and the customer has already redeemed it.\n- Snapshots `discount_id`, `discount_code`, `discount_type`, `discount_value_at_apply` and `discount_currency_code` onto the `orders` table for resilience against later discount edits or deletions.\n\n`DiscountValidator` was updated to perform the same Order-based per-user check at cart-apply time so the rejection is surfaced before checkout.\n\nUpgrade via:\n\n`composer require shopper/cart:^2.8 shopper/core:^2.8`\n`php artisan migrate`\n\n## Workarounds\n\nNone. Upgrade to `v2.8.0`.\n\n## Resources\n\n- Issue: https://github.com/shopperlabs/shopper/issues/510\n- Pull request: https://github.com/shopperlabs/shopper/pull/511\n- CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization","published":"2026-05-29T18:02:13.168Z","modified":"2026-08-12T03:51:35.223172614Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"},"epss":{"score":0.00239,"percentile":0.15113,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"shopper/cart","fixedVersion":"2.8.0"}],"fix":{"url":"https://github.com/shopperlabs/shopper/pull/511","label":"shopperlabs/shopper#511"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47741.json"},{"type":"ADVISORY","url":"https://github.com/shopperlabs/shopper/security/advisories/GHSA-9rh9-hf3w-9fgg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47741"},{"type":"REPORT","url":"https://github.com/shopperlabs/shopper/issues/510"},{"type":"FIX","url":"https://github.com/shopperlabs/shopper/pull/511"},{"type":"WEB","url":"https://github.com/shopperlabs/shopper/commit/fcd0c5920588702df5b874f432b1042abd77a50b"},{"type":"PACKAGE","url":"https://github.com/shopperlabs/shopper"},{"type":"WEB","url":"https://github.com/shopperlabs/shopper/releases/tag/v2.8.0"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:35.223172614Z"}}