CVE-2026-89435
Formidable Forms <= 6.35 - Authenticated (Subscriber+) Arbitrary Plugin Installation via 'file_url' Parameter
- State
- Published
- Severity
- 8.8 High
- Published
- Oct 30, 2026
- Updated
- Oct 30, 2026
- Reserved
- Sep 11, 2026
Description
The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Arbitrary Plugin Installation in all versions up to, and including, 6.35 via the 'file_url' parameter parameter. This is due to insufficient URL prefix validation in validate_url_is_in_s3_bucket() and a permission callback that relies solely on a shared token obtainable by any user with the delegable frm_view_forms capability, without checking install_plugins or activate_plugins capabilities. This makes it possible for authenticated attackers, with subscriber-level access and above, to install arbitrary plugins on the server. Exploitation additionally requires that the site is free-only (Formidable Pro is NOT installed).
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 8.8 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | Wordfence |
Weaknesses
- CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
Affected Products
| Product | Versions |
|---|---|
Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builderstrategy11team |
|
References
- https://www.wordfence.com/threat-intel/vulnerabilities/id/87661de6-e835-495e-9bd2-4d64b4718108?source=cve
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1514
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1489
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/helpers/FrmAppHelper.php#L4934
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1459
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAppController.php#L1167
- https://plugins.trac.wordpress.org/changeset?reponame=&new=3750372%40formidable%2Ftags%2F7.0&old=3688662%40formidable%2Ftags%2F6.35
- https://plugins.trac.wordpress.org/changeset/3746820/formidable/trunk/classes/controllers/FrmAddonsController.php
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