CVE-2026-100151

MEDIUM
Published Oct 31, 2026 CWE-79

Description

The Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder plugin for WordPress is vulnerable to Reflected DOM-Based Cross-Site Scripting via 'querystring:<key>' URL 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 execute if they can successfully trick a user into performing an action such as clicking on a link. This bypass is triggered when an attacker supplies a matching field:&lt;key&gt; URL parameter that causes the server to fully resolve the {field:*} placeholder, forcing the client-side else-branch to abandon the server-sanitized value and reconstruct field content from the raw query string.

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CVSS v3.1 Score

6.1
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0041
Probability of exploitation
0.35%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Frequently Asked Questions

What is CVE-2026-100151? +
The Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder plugin for WordPress is vulnerable to Reflected DOM-Based Cross-Site Scripting via 'querystring:<key>' URL 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 execute if they can successfully trick a user into performing an action such as clicking on a link. This bypass is triggered when an attacker supplies a matching field:&lt;key&gt; URL parameter that causes the server to fully resolve the {field:*} placeholder, forcing the client-side else-branch to abandon the server-sanitized value and reconstruct field content from the raw query string. It has a CVSS v3.1 base score of 6.1 (MEDIUM).
How severe is CVE-2026-100151? +
CVE-2026-100151 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0041, placing it in the 0th percentile for exploitation probability.
How do I check if I'm vulnerable to CVE-2026-100151? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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