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Medium

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

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-56831
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 05:19 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 15 Sept 2026, 17:42 UTC

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.

osv:CVE-2026-56831
Complete source record
{
  "id": "85dbc99b87eead2ed207234ef2764fec194039fe553982d6cf801b67961e246a",
  "url": "https://osv.dev/vulnerability/CVE-2026-56831",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Shopper: Negative discount values accepted and propagated through order calculation pipeline",
    "summary": "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.",
    "evidence": "osv:CVE-2026-56831",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-56831",
      "aliases": [
        "CVE-2026-56831",
        "GHSA-5vf4-452p-jjhf"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/shopperlabs/shopper",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "967e616281ded1a0050d9102858ecd7dd7f66a41"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.9.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "967e616281ded1a0050d9102858ecd7dd7f66a41"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "967e616281ded1a0050d9102858ecd7dd7f66a41"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.9.0"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.9.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.8.1",
            "v2.8.0",
            "v2.7.3",
            "v2.7.2",
            "v2.7.1",
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            "V1.0.4",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56831.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.647959490Z",
      "provider": "osv",
      "references": [
        "https://github.com/shopperlabs/shopper/releases/tag/v2.9.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56831.json",
        "https://github.com/shopperlabs/shopper/security/advisories/GHSA-5vf4-452p-jjhf",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-56831",
        "https://github.com/shopperlabs/shopper/commit/967e616281ded1a0050d9102858ecd7dd7f66a41",
        "https://github.com/shopperlabs/shopper/pull/528"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56831.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-56831",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 510462,
  "published_at": "2026-09-15T17:42:09.495+00:00"
}