CVE-2026-56831

Shopper is a Headless e-commerce Admin Panel. Prior to 2.9.0, the /cpanel/discounts administrative interface accepts negative fixed_amount discount values, persists them in sh_discounts, and passes them through vendor/shopper/cart/src/Discounts/DiscountCalculator.php and vendor/shopper/cart/src/Pipelines/Calculate.php without enforcing a positive-value invariant. Because the calculation subtracts discountTotal from the subtotal, a negative discount increases the resulting order total instead of reducing it. Malformed discount records can therefore cause incorrect pricing and financial data integrity failures, although the advisory does not establish a customer-facing exploitation path. This issue is fixed in version 2.9.0.

• https://github.com/shopperlabs/shopper/commit/967e616281ded1a0050d9102858ecd7dd7f66a41
• https://github.com/shopperlabs/shopper/pull/528
• https://github.com/shopperlabs/shopper/releases/tag/v2.9.0
• https://github.com/shopperlabs/shopper/security/advisories/GHSA-5vf4-452p-jjhf
• https://github.com/shopperlabs/shopper/security/advisories/GHSA-5vf4-452p-jjhf