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

Vulnerability summary

CVE-2026-103912 is a medium (CVSS 4.7) Cross-site Scripting vulnerability in jetmonsters jetformbuilder — dynamic blocks form builder. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.5% of scored vulnerabilities. Fixed in 3.6.6.1.

Timeline

1. 10-10-2026
   PublishedVulnerability first disclosed.
2. 11-10-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.