Executive brief
Ninja Forms is a popular WordPress plugin used to create and manage website forms. A security flaw allows unauthenticated users to bypass form protections, such as CAPTCHA and required field checks, by sending specially crafted data. This could lead to an influx of spam, unauthorized database entries, or the triggering of automated email notifications with unverified content.
Technical details
A vulnerability classified as Client-Side Enforcement of Server-Side Security (CWE-602) exists in Ninja Forms versions prior to 3.14.9. The flaw resides in the AJAX submission handler, where attacker-controlled field metadata is merged over server-loaded form definitions before validation occurs. An unauthenticated remote attacker can exploit this by crafting a malicious AJAX request to the 'nopriv' endpoint, allowing them to override field types, remove 'required' flags, and disable security features like CAPTCHA. This bypasses server-side validation, enabling the submission of unverified content to the database or triggering form-based actions like email notifications. The issue is resolved in version 3.14.9.
Affected products
- Saturday Drive Ninja Forms < 3.14.9
Timeline
- 2026-07-21: disclosed
- 2026-07-21: advisory
- 2026-07-21: patched: Fixed in version 3.14.9