Formidable Forms <= 6.28 - Missing Authorization to Unauthenticated Payment Integrity Bypass via PaymentIntent Reuse
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| WordPress plugin | Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More | <= 6.28 | 6.29 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- Weakness (CWE)
CWE-862- Platform
- WordPress
- Package
Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More- Disclosed
- 12.03.2026
- Updated
- 11.10.2026 10:23
Sources and licenses
Wordfence Intelligence - ebb4bc5a-9469-4733-acf3-d2dda5edb7af - Wordfence Intelligence
Copyright 1999-2026 The MITRE Corporation
Copyright 2012-2026 Defiant Inc.
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Vulnerability history: Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
All published vulnerabilities of this package (WordPress plugin), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 27
- First → latest
- 01.2016 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 4
- High 6
- Medium 17
Disclosures per year
- 2017: 4
- 2018: 0
- 2019: 1
- 2020: 0
- 2021: 2
- 2022: 2
- 2023: 4
- 2024: 6
- 2025: 0
- 2026: 6
earlier: 2
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Formidable Forms <= 6.28 - Missing Authorization to Unauthenticated Payment Integrity Bypass via PaymentIntent Reuse this entry
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