CVE-2024-3866: Ninja Forms Contact Form <= 3.8.15 - Reflected Self-Based Cross-Site Scripting via Referer

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-25 · updated 2026-06-17
Weakness: CWE-79

Description

The Ninja Forms Contact Form plugin for WordPress is vulnerable to Reflected Self-Based Cross-Site Scripting via the 'Referer' header in all versions up to, and including, 3.8.15 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Successful exploitation of this vulnerability requires "maintenance mode" for a targeted form to be enabled. However, there is no setting available to the attacker or even an administrator-level user to enable this mode. The mode is only enabled during a required update, which is a very short window of time. Additionally, because of the self-based nature of this vulnerability, attackers would have to rely on additional techniques to execute a supplied payload in the context of targeted user.

Affected products

kstover Ninja Forms – The Contact Form Builder That Grows With You: before 3.8.16 — fixed in 3.8.16

How to fix

Upgrade to a fixed version: kstover Ninja Forms – The Contact Form Builder That Grows With You 3.8.16. Check the vendor advisory for mitigations.

References

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