# CVE-2026-83537: WP Express Checkout payment verification bypass

Source: https://junglewise.ai/threats/cve-2026-83537-wp-express-checkout-payment-verification-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-09. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-83537 · Severity: medium · CVSS 5.3 · Published 2026-09-09

The WP Express Checkout WordPress plugin allows unauthenticated visitors to forge completed payment orders without actually paying. By manipulating a publicly accessible checkout form, attackers can generate valid order confirmations and access digital products meant to be purchased. This bypasses the plugin's payment gateway entirely, enabling free access to paid content.

Technologies: [WP Express Checkout](https://junglewise.ai/threats/technologies/wp-express-checkout). Vendors: [WP Express Checkout](https://junglewise.ai/threats/vendors/wp-express-checkout).

## Quick answers

**Is CVE-2026-83537 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83537 being exploited in the wild.

**How severe is CVE-2026-83537?** Medium severity, with a CVSS score of 5.3, published 9 September 2026.

**Which products and versions are affected?** WP Express Checkout before 2.5.0.

**Is there a fix for CVE-2026-83537?** A patch was published on 2026-09-09: Fixed in version 2.5.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-83537 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-83537?** Check whether you run WP Express Checkout at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The plugin fails to verify server-side that a payment was actually completed before marking an order as paid. The vulnerability exists in the wpec_process_empty_payment AJAX action, which processes free/empty payments. An unauthenticated attacker can extract the nonce and product ID from the public checkout page, then submit a forged payment request via AJAX that hardcodes the transaction status to COMPLETED without contacting any payment gateway. The plugin then generates a valid order with wpec_order_state=paid, allowing download of the product. No authentication or privilege escalation is required—the attack works entirely through public endpoints.

## Affected products

- WP Express Checkout WP Express Checkout before 2.5.0

## Timeline

- 2026-09-07: disclosed
- 2026-09-09: patched: Fixed in version 2.5.0

## References

- [https://wordpress.org/plugins](https://wordpress.org/plugins)
- [https://wpscan.com/vulnerability/02b39e4f-181d-4573-9175-bf5a6d71e531/](https://wpscan.com/vulnerability/02b39e4f-181d-4573-9175-bf5a6d71e531/)

## Related threats

- [WP Express Checkout broken access control vulnerability](https://junglewise.ai/threats/cve-2026-96818-unauthenticated-broken-access-control-in-wp-express-checkout)
- [WP Express Checkout payment verification bypass](https://junglewise.ai/threats/cve-2026-83533-wp-express-checkout-payment-verification-bypass)