CVE-2026-44826: Vvveb CMS Cart Manipulation Vulnerability

CVE-2026-44826 Overview

CVE-2026-44826 is a business logic vulnerability in Vvveb CMS, an open-source content management system with page builder capabilities for websites, blogs, and ecommerce stores. The flaw exists in the cart-add endpoint, which fails to validate the sign of the quantity parameter. Attackers can submit negative integers that propagate through line totals, subtotals, taxes, and grand totals. The resulting orders persist in the merchant database with negative totals, creating records where the merchant appears to owe the customer money. The vulnerability is classified under [CWE-1284] (Improper Validation of Specified Quantity in Input) and is fixed in version 1.0.8.2.

Critical Impact

Unauthenticated attackers can manipulate cart totals to create orders with negative values, corrupting merchant financial records and potentially triggering refund or credit workflows.

Affected Products

• Vvveb CMS versions prior to 1.0.8.2
• Vvveb ecommerce store deployments
• Vvveb-based merchant order management systems

Discovery Timeline

• 2026-05-15 - CVE-2026-44826 published to NVD
• 2026-05-18 - Last updated in NVD database

Technical Details for CVE-2026-44826

Vulnerability Analysis

The vulnerability resides in the cart management logic of Vvveb CMS. The cart-add endpoint accepts a quantity parameter from user-controlled input without verifying that the value is a positive integer. When an attacker submits a negative quantity, the server treats the request as a valid line-item addition.

The negative sign propagates through all downstream financial calculations. Line totals, subtotals, taxes, and the grand total inherit the negative value. The customer-facing cart UI then renders a negative grand total, and the checkout flow accepts the request without rejecting the anomalous state.

Once checkout completes, the order is persisted in the merchant database with a negative total column. The merchant's order management dashboard displays the order as legitimate, creating a record that no normal workflow produces.

Root Cause

The root cause is missing input validation on the sign of the quantity parameter [CWE-1284]. The application enforces type coercion to integer but omits a check that the value must be greater than zero. No business logic gate downstream rejects negative monetary totals before order persistence.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker sends a crafted HTTP request to the cart-add endpoint with a negative integer in the quantity field. The attacker then proceeds through the standard checkout flow to persist the malformed order. The vulnerability primarily impacts data integrity rather than confidentiality or availability.

The vulnerability is described in prose only — no verified proof-of-concept code is referenced. See the GitHub Security Advisory for technical details.

Detection Methods for CVE-2026-44826

Indicators of Compromise

• Orders in the merchant database with negative total, subtotal, or tax column values.
• HTTP POST requests to the cart-add endpoint containing a negative integer in the quantity parameter.
• Checkout sessions where the displayed grand total renders as a negative monetary value.
• Unexpected refund or credit ledger entries tied to newly created orders rather than prior transactions.

Detection Strategies

• Run database queries that scan the orders table for rows where total < 0 or any line-item amount is negative.
• Inspect web server access logs for cart-add requests and parse the quantity parameter for negative values.
• Apply a web application firewall rule to flag or block HTTP requests containing quantity=- patterns targeting cart endpoints.

Monitoring Recommendations

• Enable continuous integrity monitoring on ecommerce order tables to alert on negative monetary values.
• Correlate cart and checkout telemetry with order persistence events to detect anomalous workflows.
• Forward web server and application logs to a centralized data lake for retrospective hunting across the disclosure window.

How to Mitigate CVE-2026-44826

Immediate Actions Required

• Upgrade all Vvveb CMS instances to version 1.0.8.2 or later.
• Audit the orders database for any records with negative totals and reconcile against legitimate transactions.
• Review merchant refund and credit logs for activity tied to fraudulent negative-total orders.
• Restrict access to administrative order management dashboards during remediation.

Patch Information

The vulnerability is fixed in Vvveb CMS version 1.0.8.2. The patch adds validation to reject non-positive quantity values at the cart-add endpoint. Refer to the GitHub Security Advisory GHSA-75x2-j47j-mg8j for upgrade instructions and patch details.

Workarounds

• Deploy a reverse-proxy or WAF rule that rejects requests to cart endpoints when quantity is non-numeric or less than 1.
• Add a database constraint that prevents insertion of orders with negative total values until the patch is applied.
• Implement server-side input validation in custom middleware to coerce and validate the quantity parameter as a positive integer.

# Example WAF rule (ModSecurity) to block negative quantity submissions
SecRule REQUEST_URI "@contains /cart-add" \
  "chain,phase:2,deny,status:400,id:1002026,\
   msg:'CVE-2026-44826 negative quantity blocked'"
  SecRule ARGS:quantity "@lt 1" "t:none"