CVE-2026-103912

JetFormBuilder <= 3.6.6 - Reflected DOM-Based Cross-Site Scripting via 'query_var' Dynamic Preset via data-jfb-macro / JFB_FIELD:: Macro Renderer

2026-10-09 17:16
Zenith-sec

Strategic Overview

Status
Patched in 3.6.6.1
Affected Plugin
JetFormBuilder — Dynamic Blocks Form Builder
Affected Version
<= 3.6.6
CVSS
4.7Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-103912
View all JetFormBuilder — Dynamic Blocks Form Builder vulnerabilities

At a glance

CVE-2026-103912 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the JetFormBuilder WordPress plugin, affecting versions <= 3.6.6. It carries a CVSS score of 4.7 (reachable over the network). Exploitation requires no authentication. The issue is fixed in version 3.6.6.1; sites on affected versions should update now. Disclosed October 2026, reported by Zenith-sec.

Vulnerability Overview

The JetFormBuilder — Dynamic Blocks Form Builder plugin for WordPress is vulnerable to Reflected DOM-Based Cross-Site Scripting via the '<attacker-chosen query var name matching the preset's query_var setting>' parameter in all versions up to, and including, 3.6.6 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 is only exploitable on pages embedding a form that has a text field configured with a query_var Dynamic Preset and a data-jfb-macro or JFB_FIELD:: macro reference targeting that field, both of which are standard, documented plugin features.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no privileges on the target site.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Reaching this weakness in JetFormBuilder <= 3.6.6 takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For JetFormBuilder the fix is 3.6.6.1: builds <= 3.6.6 are affected, anything from 3.6.6.1 onward is not.

Remediation

Update to version 3.6.6.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to JetFormBuilder: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: JetFormBuilder 3.6.6.1 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-103912https://www.wordfence.com/threat-intel/vulnerabilities/id/e75b6080-25e8-462c-b785-dbdacc10dfe6https://nvd.nist.gov/vuln/detail/CVE-2026-103912

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C