The Formidable Forms plugin for WordPress is vulnerable to a payment integrity bypass in all versions up to, and including, 6.28. This is due to the Stripe Link return handler (handle_one_time_stripe_link_return_url) marking payment records as complete based solely on the Stripe PaymentIntent status without comparing the intent's charged amount against the expected payment amount, and the verify_intent() function validating only client secret ownership without binding intents to specific forms or actions. This makes it possible for unauthenticated attackers to reuse a PaymentIntent from a completed low-value payment to mark a high-value payment as complete, effectively bypassing payment for goods or services.

References

• https://nvd.nist.gov/vuln/detail/CVE-2026-2890
• https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controllers/FrmStrpLiteHooksController.php#L92
• https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controllers/FrmStrpLiteLinkController.php#L429
• https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controllers/FrmStrpLiteLinkController.php#L79
• https://www.wordfence.com/threat-intel/vulnerabilities/id/ebb4bc5a-9469-4733-acf3-d2dda5edb7af?source=cve