Vulnerability · Published Sep 15, 2026 · Assigned by GitHub_M
CVE-2026-56831Shopper: Negative discount values accepted and propagated through order calculation pipeline
Medium 6.5
In plain English
A medium-severity improper input validation in shopper from shopperlabs. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | shopper/framework | 2.9.0 | GHSA-5vf4-452p-jjhf |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| shopperlabs | shopper | < 2.9.0 |
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/shopperlabs/shopper/security/advisories/GHSA-5vf4-452p-jjhf x_refsource_CONFIRM
- https://github.com/shopperlabs/shopper/pull/528 x_refsource_MISC
- https://github.com/shopperlabs/shopper/commit/967e616281ded1a0050d9102858ecd7dd7f66a41 x_refsource_MISC
- https://github.com/shopperlabs/shopper/releases/tag/v2.9.0 x_refsource_MISC