JetFormBuilder — Dynamic Blocks Form Builder: Cross-site scripting

JetFormBuilder (affected: <= 3.6.5.3). An unauthenticated attacker can lure a victim to a crafted jfb_xss URL query value. A form must have a URL Query Variable preset and a Calculated Field referring to it; unsafe formula handling reflects attacker-controlled content into executable browser output. The exact processing function is unspecified.

CVE / CNA score 6.1 CVSS 3.1 · security@wordfence.com

NVD score Pending NVD has not published its own CVSS assessment.

Component: JetFormBuilder — Dynamic Blocks Form Builder
Plugin slug: jetformbuilder
Affected: <= 3.6.5.3
Safe version: 3.6.5.4
Published: Sep 25, 2026
Weakness: CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This CVE was published Sep 25, 2026 and is one of 25 known issues for this plugin.

What to do

Update, patch or deactivate.

Update to 3.6.5.4 or a later supported release. The official changelog confirms remediation for this issue. Treat preset/query values strictly as data, validate calculated formulas and escape their rendered result; remove the vulnerable field combination until updated.

A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical description

The JetFormBuilder — Dynamic Blocks Form Builder plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'jfb_xss' (URL Query Variable) Parameter via Calculated Field in all versions up to, and including, 3.6.5.3 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. Exploitation requires the targeted page to host a form configured with both a URL Query Variable preset field and a Calculated Field that references it, which are standard plugin features.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Primary and upstream sources

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