The Integration for Google Sheets and Contact Form 7, WPForms, Elementor, Ninja Forms plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.1.1 via deserialization of untrusted input within the verify_field_val() function. This makes it possible for unauthenticated attackers to inject a PHP Object. The additional presence of a POP chain in the Contact Form 7 plugin, which is likely to be used alongside, allows attackers to delete arbitrary files, leading to a denial of service or remote code execution when the wp-config.php file is deleted.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.