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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-56831: 0.43% estimated exploitation activity in the next 30 days; percentile 37.88 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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: The application accepted these values without…

Published by the source

11 Sep 2026, 21:28 UTC

Last modified by the source

11 Sep 2026, 21:45 UTC

Source last checked

26 Oct 2026, 14:53 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5vf4-452p-jjhf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5vf4-452p-jjhf

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# Patch Next advisory brief: CVE-2026-56831

Advisory: Shopper: Negative discount values accepted and propagated through order calculation pipeline
IDs: CVE-2026-56831, GHSA-5vf4-452p-jjhf
Record: https://patchnext.com/advisories/cve-2026-56831 (revision 2, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: shopper/framework 2.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist shopper/framework: affected < 2.9.0; fixed in 2.9.0

## Suggested inspection (read-only)
- Packagist shopper/framework: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on shopper/framework.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5vf4-452p-jjhf (OSV record GHSA-5vf4-452p-jjhf lists affected ranges: Packagist shopper/framework >=0 <2.9.0 (fixed))
- Verified: https://github.com/advisories/GHSA-5vf4-452p-jjhf (GitHub-reviewed advisory GHSA-5vf4-452p-jjhf lists affected ranges: Packagist shopper/framework >=0 <2.9.0)

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