CVE-2026-89435 json
Formidable Forms <= 6.35 - Authenticated (Subscriber+) Arbitrary Plugin Installation via 'file_url' Parameter
published 2026-10-30 10 d ago modified 2026-10-30 9 d ago also EUVD-2026-113736
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 33%
- public exploits
- 0
- none known
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 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).
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 9 d ago
Exploit prediction
0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- strategy11team Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder
Classification
- Weakness
-
- CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
- Technology feeds
References
- wordfence.com /threat-intel/vulnerabilities/id/87661de6-e835-495e-9bd2-4d64b4718108?source=cve
- plugins.trac.wordpress.org /browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1514
- plugins.trac.wordpress.org /browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1489
- plugins.trac.wordpress.org /browser/formidable/tags/6.35/classes/helpers/FrmAppHelper.php#L4934
- plugins.trac.wordpress.org /browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1459
- plugins.trac.wordpress.org /browser/formidable/tags/6.35/classes/controllers/FrmAppController.php#L1167
- plugins.trac.wordpress.org /changeset?reponame=&new=3750372%40formidable%2Ftags%2F7.0&old=3688662%40formidable%2Ftags%2F6.35
- plugins.trac.wordpress.org /changeset/3746820/formidable/trunk/classes/controllers/FrmAddonsController.php
Sources
- CVE List CVE-2026-89435
- NVD CVE-2026-89435
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.