The vulnerability in the Ninja Forms plugin stems from its improper handling of sensitive data within its codebase, specifically through a callback function tied to the admin_enqueue_scripts action in blocks/bootstrap.php. Attackers with Contributor-level privileges can exploit this flaw to retrieve an authorization token. This token provides unauthorized access to the content of form submissions, potentially exposing sensitive user data. Such data could include personal information, email addresses, or any confidential content submitted via forms. This exposure presents a significant privacy risk to site users and an operational risk to the administrators, as the information could be misused to harm users or discredit the organization. It is crucial for site administrators to address this vulnerability promptly.

To mitigate this vulnerability, restrict the access and capabilities of Contributor-level users if possible. Regularly audit user roles and permissions to ensure only necessary access is granted. Implement logging and monitoring of admin actions to detect any unauthorized access attempts.