WordPress security changelog
HIGH CVE-2026-89435 Received

Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder: Unauthorized plugin installation

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). The structured affected range is <= 6.35.

CVE / CNA score 8.8 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder
Plugin slug
formidable
Affected
<= 6.35
Safe version
7.0
Published
Oct 30, 2026
Weakness
CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

This CVE was published Oct 30, 2026 and is one of 12 known issues for this plugin.

What to do

Update, patch or deactivate.

Update to a supported release containing the confirmed fix: 7.0. Require plugin-installation and activation capabilities and validate the full trusted download origin before retrieving a package. Official author notes: https://wordpress.org/plugins/formidable/#developers.

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 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).

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

References

Primary and upstream sources