CVE-2026-109384: The Innovative Form Builder <= 1.5.1 - Authenticated (Custom+) Arbitrary File Upload via 'allowedFileExtensions' Configuration + Public /form/submission/ Multipart Upload

Q: Who needs access to exploit this issue, and can an unauthenticated attacker use it alone?

An attacker needs an authenticated WordPress account with custom-level access and the add_edit_forms capability to configure a File Upload field that permits a dangerous extension. An unauthenticated visitor can then submit the malicious file through the public form submission REST endpoint, but cannot set up the vulnerable form configuration alone.

Q: Is a default IvyForms installation immediately exposed to executable-file uploads?

Exploitation requires a privileged authenticated user to explicitly configure a File Upload field with a dangerous extension, such as php, in its allowed-extensions list and publish the form. The provided information does not indicate that such an extension is allowed by default.

Q: What mitigation is available if updating is not immediately possible?

Review published forms with File Upload fields and remove dangerous or executable extensions from their allowed-extensions lists. Restrict the add_edit_forms capability to trusted users and consider disabling or restricting public access to affected upload forms and the /wp-json/ivyforms/v1/form/submission/ route.

Q: How can administrators identify potentially affected configurations?

Inspect IvyForms File Upload field settings for published forms, focusing on allowed-extensions lists that include dangerous extensions such as php. Also review which accounts have the add_edit_forms capability, since those accounts can create the configuration required for exploitation.

Published Oct 28, 2026

Updated

The The Innovative Form Builder – IvyForms plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.5.1 via the filterFiletypeAndExt function. This is due to insufficient file type validation due to the absence of a dangerous-extension denylist in the allowed-extensions sanitizer and deliberate override of WordPress's native MIME and extension defences via a registered wpcheckfiletypeandext filter. This makes it possible for authenticated attackers, with custom-level access and above, to upload files that may be executable, which makes remote code execution possible. An authenticated attacker with the custom addeditforms capability must first configure a File Upload field with a dangerous extension (e.g., php) in the allowed-extensions list; once that form is published, any unauthenticated visitor can trigger the actual file upload via the publicly accessible /wp-json/ivyforms/v1/form/submission/ REST route.

Affected Software

1 affected component

IvyForms Innovative Form Builder – IvyForms<=1.5.1

Event History

Oct 28, 2026

CVE Published

via MITRE·06:45 AM

Data Sourced

via MITRE·06:45 AM

DescriptionSeverityWeakness

Frequently Asked Questions

Who needs access to exploit this issue, and can an unauthenticated attacker use it alone?

An attacker needs an authenticated WordPress account with custom-level access and the add_edit_forms capability to configure a File Upload field that permits a dangerous extension. An unauthenticated visitor can then submit the malicious file through the public form submission REST endpoint, but cannot set up the vulnerable form configuration alone.

Is a default IvyForms installation immediately exposed to executable-file uploads?

Exploitation requires a privileged authenticated user to explicitly configure a File Upload field with a dangerous extension, such as php, in its allowed-extensions list and publish the form. The provided information does not indicate that such an extension is allowed by default.

What mitigation is available if updating is not immediately possible?

Review published forms with File Upload fields and remove dangerous or executable extensions from their allowed-extensions lists. Restrict the add_edit_forms capability to trusted users and consider disabling or restricting public access to affected upload forms and the /wp-json/ivyforms/v1/form/submission/ route.

How can administrators identify potentially affected configurations?

Inspect IvyForms File Upload field settings for published forms, focusing on allowed-extensions lists that include dangerous extensions such as php. Also review which accounts have the add_edit_forms capability, since those accounts can create the configuration required for exploitation.

CVE-2026-109384: The Innovative Form Builder <= 1.5.1 - Authenticated (Custom+) Arbitrary File Upload via 'allowedFileExtensions' Configuration + Public /form/submission/ Multipart Upload

Affected Software

Event History

Frequently Asked Questions

Who needs access to exploit this issue, and can an unauthenticated attacker use it alone?

Is a default IvyForms installation immediately exposed to executable-file uploads?

What mitigation is available if updating is not immediately possible?

How can administrators identify potentially affected configurations?

Company

Resources

Contact

Frequently Asked Questions

Who needs access to exploit this issue, and can an unauthenticated attacker use it alone?

Is a default IvyForms installation immediately exposed to executable-file uploads?

What mitigation is available if updating is not immediately possible?

How can administrators identify potentially affected configurations?