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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controll…
security@wordfence.com
https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controll…
security@wordfence.com
https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controll…
security@wordfence.com
https://www.wordfence.com/threat-intel/vulnerabilities/id/ebb4bc5a-9469-4733-ac…
security@wordfence.com