The Donations Widget plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 3.19.4 via deserialization of untrusted input from the Donation Form through the 'card_address' parameter. This makes it possible for unauthenticated attackers to inject a PHP Object. The additional presence of a POP chain allows attackers to achieve remote code execution.
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.