This vulnerability is caused by an oversight in the plugin's code, specifically within the 'rednumber_duplicate' function. It lacks proper capability checks, which inadvertently permits lower-privileged users, like those with Subscriber-level access, to duplicate posts. These can include sensitive ones marked as private or password-protected. The lack of appropriate permission verification means that users without sufficient clearance can access and replicate confidential content, potentially leading to information leakage. This vulnerability can be especially concerning for websites that rely on user-role management to protect sensitive posts. An attacker leveraging this flaw could compromise site integrity by creating unauthorized copies of restricted content.

Site administrators should immediately restrict access to the plugin for non-administrative users. Evaluate user roles and ensure that least privilege is enforced across the platform to minimize risk exposure. Additionally, monitor your WordPress site for any unauthorized post activities as a precaution.