CVE-2026-56831: Shopper: Negative discount values accepted and propagated through order calculation pipeline

The Shopper Framework discount management functionality accepts negative discount values without server-side validation.

It was confirmed that negative fixed-amount discounts can be created through the administrative interface, persisted to the database, and subsequently processed by the cart/order calculation pipeline.

The application appears to assume that discount values are always positive but does not enforce this assumption during creation, storage, or calculation.

As a result, malformed discount records can influence financial calculations and produce unintended order totals.