The Last Viewed Posts by WPBeginner plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.0.0 via deserialization of untrusted input from the LastViewedPosts Cookie. This makes it possible for unauthenticated attackers to inject a PHP Object. No known POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.