PT-2026-90547 · Packagist · Shopper/Framework

CVE-2026-56831

·

Published

2026-09-11

·

Updated

2026-09-11

CVSS v3.1

6.5

Medium

VectorAV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Summary

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.

Affected Product

Package: shopper/framework
Version Tested: 2.8.1

Vulnerability Type

  • Business Logic Vulnerability
  • Improper Input Validation (CWE-20)

Description

While reviewing the discount functionality, it was discovered that the application accepts negative discount values through the administrative interface.
Example values tested:
text
-50.00
-99,999,999.00
The application accepted these values without validation and stored them in the database.
Example records observed in the sh discounts table:
text
1 | QCZ5Y3HESM | fixed amount | -5000
4 | TOZKAHCB4S | fixed amount | -9999999900
This demonstrates that negative discount values are successfully persisted.

Steps to Reproduce

1. Create a Discount

Login as an administrator.
Navigate to:
text
/cpanel/discounts
Create a new discount with the following values:
text
Type: fixed amount
Value: -99999999
Save the discount.

2. Observe Successful Creation

The discount is accepted by the application and displayed in the administration interface.
Example:
text
Code: TOZKAHCB4S
Amount: -$99,999,999.00

3. Verify Database Persistence

Inspect the database:
sql
select * from sh discounts;
Observed entry:
text
TOZKAHCB4S | fixed amount | -9999999900

Technical Analysis

Discount Calculation

File:
text
vendor/shopper/cart/src/Discounts/DiscountCalculator.php
Observed code:
php
$fixedAmount = $discount->value;
The value is later processed without validation:
php
$fixedAmount = min($fixedAmount, $applicableSubtotal);
When a negative value is supplied:
php
min(-9999999900, 10000)
returns:
php
-9999999900
allowing the negative value to continue through the calculation pipeline.
The resulting adjustment values are inserted into the database:
php
CartLineAdjustment::query()->insert($adjustments);
No validation was identified to ensure that discount amounts are positive before calculations occur.

Final Total Calculation

File:
text
vendor/shopper/cart/src/Pipelines/Calculate.php
Observed logic:
php
$context->total = max(
  0,
  $context->taxInclusive
    ? $context->subtotal - $context->discountTotal
    : $context->subtotal - $context->discountTotal + $context->taxTotal
);
Because negative discount values are allowed to reach this stage, financial calculations are performed using malformed discount data.
Example:
text
Subtotal   = 10000
DiscountTotal = -5000
Resulting calculation:
text
10000 - (-5000)
Result:
text
15000
This demonstrates that negative discount values directly affect order total calculations.

Impact

The following was confirmed:
  • Negative discount values are accepted.
  • Negative discount values are persisted.
  • Negative discount values are processed by the discount calculation engine.
  • Negative discount values affect order total calculations.
Potential consequences include:
  • Incorrect pricing calculations.
  • Financial data integrity issues.
  • Unexpected order totals.
  • Violated assumptions within downstream pricing logic.
  • Future vulnerabilities if additional components assume discount values are always positive.
Because Shopper is a headless e-commerce administration framework and does not ship with a customer-facing storefront, it was not verified a customer-facing exploitation path.
However, malformed discount records currently propagate through pricing calculations without validation.

Recommendation

Implement server-side validation enforcing positive discount values before persistence and before entering the calculation pipeline.
Suggested validation:

Fixed Amount Discounts

text
value > 0

Percentage Discounts

text
0 < value <= 100
Additionally, existing discount records should be validated before calculation to prevent malformed data from influencing pricing logic.

Environment

text
Shopper Framework 2.8.1
Laravel 12.61.1
PHP 8.4.16
SQLite

Fix

RCE

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dbugs@ptsecurity.com

Weakness Enumeration

CWE-20

Related Identifiers

CVE-2026-56831
GHSA-5VF4-452P-JJHF

Affected Products

Shopper/Framework