Arbitrary Plugin Installation Vulnerability in Formidable Forms by WordPress
CVE-2026-89435

8.8HIGH

Key Information:

Vendor

WordPress
Status
Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder
Vendor
CVE Published:
30 October 2026

What is CVE-2026-89435?

The Formidable Forms plugin for WordPress is susceptible to a vulnerability that allows authenticated users with subscriber-level permissions and above to install arbitrary plugins on the server. This occurs due to inadequate validation of the 'file_url' parameter in the validate_url_is_in_s3_bucket function and reliance on a shared token for permissions that do not verify installation capabilities. The vulnerability is present in all versions up to and including 6.35, and it is critical for site owners to ensure they are using the latest version to mitigate potential security risks.

Affected Version(s)

Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder 0 <= 6.35

References

https://www.wordfence.com/threat-intel/vulnerabilities/id...
https://plugins.trac.wordpress.org/browser/formidable/tag...
https://plugins.trac.wordpress.org/browser/formidable/tag...

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Supakiad S. (m3ez)
.