CVE-2026-4883: Piotnet Forms <= 2.1.40 - Unauthenticated Arbitrary File Upload via Form File Upload
The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetformsajaxformbuilder' 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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-4883?
CVE-2026-4883 is a high-severity vulnerability due to the potential for unauthenticated arbitrary file uploads.
How do I fix CVE-2026-4883?
To mitigate CVE-2026-4883, upgrade Piotnet Forms to version 2.1.41 or later where the issue has been addressed.
What are the consequences of exploiting CVE-2026-4883?
Exploitation of CVE-2026-4883 allows attackers to upload malicious files, which can lead to site compromise or data breaches.
Which versions of Piotnet Forms are affected by CVE-2026-4883?
CVE-2026-4883 affects all versions of Piotnet Forms up to and including 2.1.40.
Is authentication required to exploit CVE-2026-4883?
No, CVE-2026-4883 can be exploited without authentication, making it particularly dangerous.