CVE-2026-109997
Received Received - Intake

Stored XSS in Ninja Forms WordPress Plugin

Publication date: 2026-10-31

Last updated on: 2026-10-31

Assigner: Wordfence

Description
The Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'formData.extra' parameter in all versions up to, and including, 3.15.5 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The nf_ajax_submit endpoint issues a valid nonce to any requester on failure, effectively neutralizing the nonce check and making exploitation trivially achievable in a single unauthenticated request.

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Meta Information

Published
2026-10-31
Last Modified
2026-10-31
Generated
2026-10-31
AI Q&A
2026-10-31
EPSS Evaluated
N/A
NVD
CVE-2026-109997
EUVD
EUVD-2026-114576

Affected Vendors & Products

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a Stored Cross-Site Scripting (XSS) vulnerability in the Ninja Forms WordPress plugin. It allows unauthenticated attackers to inject malicious scripts via the 'formData.extra' parameter due to poor input sanitization and output escaping. The vulnerability is exploitable through the nf_ajax_submit endpoint, which issues a valid nonce even on failure, bypassing security checks.

Detection Guidance

To detect this vulnerability, inspect WordPress sites using Ninja Forms versions up to 3.15.5 for suspicious form submissions or scripts in the 'formData.extra' parameter. Check server logs for requests to the nf_ajax_submit endpoint with unauthenticated access.

Impact Analysis

An attacker could inject malicious scripts into your WordPress site, which would execute when users visit affected pages. This could lead to theft of user sessions, defacement of your site, or redirection to malicious sites. Since it requires no authentication, the risk is high for all users of vulnerable versions.

Compliance Impact

This vulnerability could lead to unauthorized access to user data, violating GDPR's data protection requirements and HIPAA's safeguards for protected health information. A successful exploit may result in data breaches, triggering compliance violations and potential fines.

Mitigation Strategies

Immediately update Ninja Forms to the latest version beyond 3.15.5. If an update is unavailable, disable the plugin temporarily. Review all forms for injected scripts and remove any unauthorized content.

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