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Vulnerability · Published Oct 31, 2026 · Assigned by Wordfence

CVE-2026-109997Ninja Forms <= 3.15.5 - Unauthenticated Stored Cross-Site Scripting via 'extra' Parameter via Metadata Key Normalization

High 7.2

In plain English

A high-severity cross-site scripting in Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder from kstover. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities).

Severity (CVSS 3.1)7.2High
Exploit odds (30 days)0.4%top 61.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

VendorProductVersions
kstover Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder 0 – through 3.15.5

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

References