CVE-2026-109997
Ninja Forms <= 3.15.5 - Unauthenticated Stored Cross-Site Scripting via 'extra' Parameter via Metadata Key Normalization
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.
| CWE | CWE-79 |
| Vendor | kstover |
| Product | ninja forms – contact form builder with calculators, quizzes, signatures & ai form builder |
| Published | Oct 31, 2026 |
Get instant alerts for kstover ninja forms – contact form builder with calculators, quizzes, signatures & ai form builder
Be the first to know when new high vulnerabilities affecting kstover ninja forms – contact form builder with calculators, quizzes, signatures & ai form builder are published — delivered to Slack, Telegram or Discord.
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N