CVE-2026-56831

MEDIUM 6.5

Shopper: Negative discount values accepted and propagated through order calculation pipeline

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-20
Vendor	shopperlabs
Product	shopper
Published	Sep 15, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

shopperlabs / shopper

< 2.9.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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