---
id: CVE-2026-89435
title: >-
  Formidable Forms <= 6.35 - Authenticated (Subscriber+) Arbitrary Plugin
  Installation via 'file_url' Parameter
summary: >-
  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 para…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-74
vendor: strategy11team
product: >-
  Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form &
  Custom Form Builder
affected:
  - >-
    formidable_forms_contact_form_survey_quiz_payment_calculator_form_custom_form_builder
    <= 6.35
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-30T17:32:42.670504Z'
published: '2026-10-30'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T18:09:00.504Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89435'
references:
  - url: >-
      https://www.wordfence.com/threat-intel/vulnerabilities/id/87661de6-e835-495e-9bd2-4d64b4718108?source=cve
  - url: >-
      https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1514
  - url: >-
      https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1489
  - url: >-
      https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/helpers/FrmAppHelper.php#L4934
  - url: >-
      https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1459
  - url: >-
      https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAppController.php#L1167
  - url: >-
      https://plugins.trac.wordpress.org/changeset?reponame=&new=3750372%40formidable%2Ftags%2F7.0&old=3688662%40formidable%2Ftags%2F6.35
  - url: >-
      https://plugins.trac.wordpress.org/changeset/3746820/formidable/trunk/classes/controllers/FrmAddonsController.php
tags:
  - cve.org
epss: 0.00392
epssPercentile: 0.33623
ingestedAt: '2026-11-05T16:24:31.316Z'
---

## Overview

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).

## Affected

- `formidable_forms_contact_form_survey_quiz_payment_calculator_form_custom_form_builder <= 6.35`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.