The CMB2 plugin for WordPress has a security issue that allows attackers to inject a type of code called PHP Object. This can happen if the plugin receives information from a certain part of the website. This vulnerability can only be exploited by people who have permission to make changes to the website. If there is another plugin or theme installed on the website that also has a security issue, the attacker could potentially do more harm by deleting files, accessing sensitive information, or running their own code. It’s important to mention that this plugin is mainly used by developers and the vulnerability can only be exploited if certain code is present in the website’s design.