Description
WordPress Plugin Formidable Form Builder-Contact Form, Survey & Quiz Forms for WordPress is prone to a vulnerability that lets remote attackers inject and execute arbitrary code because the application fails to sanitize user-supplied input before being passed to the unserialize() PHP function. Attackers can possibly exploit this issue to execute arbitrary PHP code within the context of the affected webserver process. WordPress Plugin Formidable Form Builder-Contact Form, Survey & Quiz Forms for WordPress version 4.02 is vulnerable; prior versions may also be affected.
Remediation
Update to plugin version 4.02.03 or latest
References
https://pentest.co.uk/labs/advisory/cve-2019-15780/
https://raw.githubusercontent.com/Strategy11/formidable-forms/master/changelog.txt