Quick answers
- Is CVE-2026-83533 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-83533 being exploited in the wild.
- How severe is CVE-2026-83533?
- Medium severity, with a CVSS score of 5.3, published 2 September 2026.
- Which products and versions are affected?
- WP Express Checkout before 2.4.9.
- Is there a fix for CVE-2026-83533?
- A patch was published on 2026-09-02: Fixed in version 2.4.9 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-83533 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-83533?
- 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
This is a server-side request forgery (SSRF) and authentication bypass vulnerability in the plugin's wpec_process_payment AJAX endpoint. The vulnerable component does not verify that a payment gateway (PayPal) actually processed a transaction before accepting payment status from the client. An unauthenticated attacker can extract the nonce, product ID, and price from the public product page, then submit a forged POST request with status=COMPLETED and arbitrary transaction details. The plugin accepts the fake payment and creates a paid order post without contacting the payment gateway, granting access to the digital product. No user interaction or authentication is required; the attack succeeds against any WP Express Checkout installation with a published product. Versions before 2.4.9 are vulnerable; a patch is available.
Affected products
- WP Express Checkout WP Express Checkout before 2.4.9
Timeline
- 2026-09-01: disclosed
- 2026-09-02: patched: Fixed in version 2.4.9