Attack Chain

1. An unauthenticated attacker identifies a target WordPress website utilizing the Ninja Forms plugin, version 3.14.8 or prior.
2. The attacker locates a form on the website that incorporates ListSelect or ListRadio fields designed to influence calculations or payment totals.
3. The attacker intercepts or crafts a legitimate form submission payload destined for the /wp-admin/admin-ajax.php endpoint, specifically targeting the action=nf_ajax_submit request.
4. The attacker modifies the intercepted payload to inject arbitrary numeric values into form fields that are meant to be ListSelect or ListRadio choices, even if these values are not part of the form's legitimate configuration.
5. The maliciously crafted payload is then sent to the ajax submit endpoint of the vulnerable Ninja Forms plugin.
6. Due to the improper input validation vulnerability, the plugin's get_calc_value() method processes these attacker-controlled numeric values as legitimate inputs.
7. This processing results in the manipulation of subsequent form calculations, including payment totals.
8. The attacker successfully bypasses the website's configured pricing logic, potentially acquiring goods or services at a reduced or zero cost.

Impact

The successful exploitation of CVE-2026-65052 can lead to severe financial consequences for organizations using the Ninja Forms WordPress plugin for e-commerce or donation collection. Attackers can effectively manipulate payment amounts, causing a direct loss of revenue by reducing transaction totals to zero or arbitrary low figures. This vulnerability directly impacts the integrity of financial transactions processed through Ninja Forms, potentially leading to widespread fraud and undermining customer trust. While specific victim counts are not provided, any website running affected versions of the plugin with forms tied to monetary transactions is at risk.

Recommendation

• Immediately patch the Ninja Forms WordPress plugin to a version greater than 3.14.8 to remediate CVE-2026-65052.
• Regularly review web server access logs for /wp-admin/admin-ajax.php with action=nf_ajax_submit requests, looking for suspicious patterns in POST body data that may indicate attempts to inject non-configured numeric values into form fields.