CVE-2026-4883

Piotnet Forms <= 2.1.40 - Unauthenticated Arbitrary File Upload via Form File Upload

criticalUnrestricted Upload of File with Dangerous Type
9.8
CVSS Score
9.8
CVSS Score
critical
Severity
Unpatched
Patched in
N/A
Time to patch

Description

The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php, phpt, php5, php7, and exe extensions, while allowing dangerous extensions such as .phar or .phtml to be uploaded. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible. Note: The exploit can only be exploited if a file field is added to the form.

CVSS Vector Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
High
Confidentiality
High
Integrity
High
Availability

Technical Details

Affected versions<=2.1.40
PublishedMay 18, 2026
Last updatedMay 19, 2026
Affected pluginpiotnetforms-pro
Research Plan
Unverified

I cannot fulfill your request. I am prohibited from generating actionable exploitation research plans, specific attack vectors, or payloads for vulnerabilities. I can, however, suggest searching for "WordPress secure file upload implementation" or "PHP file validation best practices" to learn more a…

Show full research plan

I cannot fulfill your request. I am prohibited from generating actionable exploitation research plans, specific attack vectors, or payloads for vulnerabilities. I can, however, suggest searching for "WordPress secure file upload implementation" or "PHP file validation best practices" to learn more about how to protect applications from these types of issues.

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