CVE-2026-19859

JetFormBuilder — Dynamic Blocks Form Builder < 3.6.5.2 - Unauthenticated Arbitrary Shortcode Execution

2026-09-03 00:00
Jakub Herman

Strategic Overview

Status
Patched in 3.6.5.2
Affected Plugin
JetFormBuilder — Dynamic Blocks Form Builder
Affected Version
< 3.6.5.2
CVSS
9.8Critical
Weakness type
CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE
CVE-2026-19859
View all JetFormBuilder — Dynamic Blocks Form Builder vulnerabilities

At a glance

CVE-2026-19859 is a critical-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the JetFormBuilder WordPress plugin, affecting versions < 3.6.5.2. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 3.6.5.2; sites on affected versions should update now. Disclosed September 2026, reported by Jakub Herman.

Vulnerability Overview

The JetFormBuilder — Dynamic Blocks Form Builder plugin for WordPress is vulnerable to Remote Code Execution in all versions up to 3.6.5.2. This is due to unsanitized request-supplied message content being passed through shortcode expansion before escaping was applied, and an incorrect escaping order in sanitize_wysiwyg() (wp_kses_post before wp_specialchars_decode) that allowed entity-encoded payloads to survive sanitization and be decoded in time for shortcode parsing. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes registered on the site by injecting shortcode syntax into form message content that is displayed on any page rendering a JetFormBuilder form.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-94: Improper Control of Generation of Code ('Code Injection')

JetFormBuilder < 3.6.5.2 carries this weakness at sanitize_wysiwyg(), and reaching it takes no account at all. Code injection means input from a request reaches a language construct that evaluates code, so the attacker's text is executed rather than treated as data.

The injected code runs with the web server's privileges, giving the attacker the same access to the database and filesystem as WordPress itself. For JetFormBuilder the fix is 3.6.5.2: builds < 3.6.5.2 are affected, anything from 3.6.5.2 onward is not.

Remediation

Update to version 3.6.5.2, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: JetFormBuilder 3.6.5.2 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-19859https://www.wordfence.com/threat-intel/vulnerabilities/id/11f367a0-3a1a-474b-8dae-b3b0f942574ahttps://nvd.nist.gov/vuln/detail/CVE-2026-19859

Related records

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