The Ninja Forms WordPress plugin before 3.14.10 does not prevent user-supplied query-string input, used to pre-populate a form field's default value, from being processed as a shortcode, allowing unauthenticated attackers to execute arbitrary shortcodes registered on the site when a form so configured is embedded on a public page.

Ninja Forms WordPress plugin version 3.14.8 and prior contains a missing authorization vulnerability in the render callback of the ninja-forms/submissions-table Gutenberg block that allows authenticated attackers with Author-level privileges to expose stored form submissions to unauthenticated visitors by embedding the block with an arbitrary formID on a published post. Attackers can retrieve the signed bearer token injected into every page visitor's browser via wplocalizescript and use it against the REST API submissions endpoint to access all saved form submission field values, including sensitive personally identifiable information such as names, email addresses, and phone numbers.

Ninja Forms WordPress plugin version 3.14.8 contains a client-side enforcement of server-side security vulnerability that allows unauthenticated attackers to bypass all form validation by merging attacker-controlled field metadata over server-loaded form definitions before validation runs. Attackers can craft a malicious AJAX submission overriding field types, removing required flags, and disabling CAPTCHA checks through the nopriv AJAX endpoint to trigger form actions such as email notifications and database storage with unverified, attacker-controlled content.