Formidable Forms <= 6.34 - Unauthenticated Arbitrary Shortcode Execution
Strategic Overview
- Status
- Patched in 6.35
- Affected Plugin
- Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
- Affected Version
<= 6.34- CVSS
- 6.5Medium
- Weakness type
- CWE-94 · Improper Control of Generation of Code ('Code Injection')
- CVE
CVE-2026-19857
At a glance
CVE-2026-19857 is a medium-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the Formidable Forms WordPress plugin, affecting versions <= 6.34. It carries a CVSS score of 6.5 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 6.35; sites on affected versions should update now. Disclosed September 2026, reported by Jakub Herman.
Vulnerability Overview
The Formidable Forms plugin for WordPress is vulnerable to Arbitrary Shortcode Execution in all versions up to, and including, 6.34. This is due to the use of do_shortcode() on user supplied input. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes registered on the site. The impact depends on which shortcodes the site has registered, so a site running a plugin whose shortcodes expose data or perform actions is affected more severely.
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.
CWE-94: Improper Control of Generation of Code ('Code Injection')
Formidable Forms <= 6.34 carries this weakness at do_shortcode(), 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 Formidable Forms the fix is 6.35: builds <= 6.34 are affected, anything from 6.35 onward is not.
Remediation
Update to version 6.35, 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: Formidable Forms 6.35 closes this, and updating the plugin is the step that ends it.
- Firewall
- Scanner
- Login Security
External References
Related records
Other vulnerabilities in Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
- 9.8CVE-2023-1405: Formidable Forms <= 6.1.2 PHP Object Injection
CVE-2023-1405 - 9.8CVE-2019-15780: Formidable Form Builder <= 4.02 PHP Object Injection
CVE-2019-15780 - 9.6CVE-2021-24884: Formidable Form Builder <= 4.09.04 Stored XSS
CVE-2021-24884 - 9.1Formidable Form Builder <= 2.0.21 Missing Authorization Checks
- 8.8CVE-2014-9309: Formidable Form Builder <= 1.07.11 SQL Injection
CVE-2014-9309 - 8.6Formidable Form Builder < 2.05.03 SQL Injection
- 8.3CVE-2017-20192: Formidable Form Builder < 2.05.03 Stored XSS
CVE-2017-20192 - 7.5CVE-2026-2890: Formidable… Unauthenticated Payment Integrity Bypass
CVE-2026-2890
Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C