Formidable Forms <= 6.35 — Authenticated (Subscriber+) Arbitrary Plugin Installation via 'file_url' Parameter
CVE-2026-89435Published · Updated Action summary
Affected: ≤6.35Update to 7.0 or newer
All remediation steps- Severity
- High8.8
- CVSS
- 8.8CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HWhat does this vector mean?
AV:NAttack vector- Network
AC:LAttack complexity- Low
PR:LPrivileges required- Low
UI:NUser interaction- None
S:UScope- Unchanged
C:HConfidentiality- High
I:HIntegrity- High
A:HAvailability- High
- Required access
- Unknown
- Exploit prediction (EPSS)
- 0.4% chance in 30 days33th percentile
- CISA KEV
- Not listed
On this page8
Am I affected?
Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder formidable
- Affected≤ 6.35
- Patched in7.0
Update to 7.0 or newer.
You are affected if you run ≤ 6.35. Version 7.0 and later are not affected by this issue.
- Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder.
- No admin access? Run a passive check of your site. It reads public files only.
What to do
- Update to version 7.0, or a newer patched version
- Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
- Watch Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder to get an email when the next vulnerability is published.
Advisory
Source description from Wordfence Intelligence, credited to Supakiad S. (m3ez).
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).
Exploits & references
Proof-of-concept & detection
No public proof-of-concept or detection template is known for this vulnerability.
Advisories & patches
- Advisorywordfence.com
Related CVEs
More in Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder
All 29| Severity | Vulnerability | CVE | Published |
|---|---|---|---|
| High7.5 | Unauthenticated Denial of Service <7.0Update to 7.0 | CVE-2026-85642 | |
| Medium5.3 | Unauthenticated Content Injection ≤6.34Update to 6.35 | CVE-2026-85641 | |
| Medium6.5 | Unauthenticated Arbitrary Shortcode Execution ≤6.34Update to 6.35 | CVE-2026-19857 | |
| High7.2 | Unauthenticated Stored Cross-Site Scripting via 'frm_user_id' Parameter ≤6.33.1Update to 6.34 | CVE-2026-18331 | |
| Medium5.3 | Unauthenticated Payment Bypass ≤6.32.0Update to 6.32.1 | CVE-2026-11361 |
- High7.5Unauthenticated Denial of Service
<7.0Update to 7.0
- Medium5.3Unauthenticated Content Injection
≤6.34Update to 6.35
- Medium6.5Unauthenticated Arbitrary Shortcode Execution
≤6.34Update to 6.35
- High7.2Unauthenticated Stored Cross-Site Scripting via 'frm_user_id' Parameter
≤6.33.1Update to 6.34
- Medium5.3Unauthenticated Payment Bypass
≤6.32.0Update to 6.32.1
Timeline
CVE published
Severity high, CVSS 8.8
Record last updated
Sources & licenses
Wordfence record- Vulnerability data
- Wordfence Intelligence. Copyright 2012-2026 Defiant Inc. Licensed under the CC BY-SA 4.0.
- CVE® identifiers
- Copyright 1999-2026 The MITRE Corporation. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
- CVSS / CWE
- National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
- EPSS
- Exploit Prediction Scoring System by FIRST.org.
- VulnCrest content
- Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.