Vulnerability Description
The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 6.1.17. This is due to the PayPal IPN (Instant Payment Notification) verification being disabled by default (`disable_ipn_verification` defaults to `'yes'` in `PayPalSettings.php`). This makes it possible for unauthenticated attackers to send forged PayPal IPN notifications to the publicly accessible IPN endpoint, marking unpaid form submissions as "paid" and triggering post-payment automation (emails, access grants, digital product delivery).
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://fluentforms.com/docs/changelog/#2-toc-title
- https://www.wordfence.com/threat-intel/vulnerabilities/id/e5c62e54-da06-4b44-ba7
FAQ
What is CVE-2026-2428?
CVE-2026-2428 is a vulnerability with a CVSS score of 7.5 (HIGH). The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 6.1.17. This is due to the PayPal IPN (Insta...
How severe is CVE-2026-2428?
CVE-2026-2428 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-2428?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.