CVE-2026-4883 Piotnet Forms <= 2.1.40 - Unauthenticated Arbitrary File Upload via Form File Upload
Unauthenticated attackers can upload malicious files via forms if a file field is present, potentially leading to remote code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-4883?
CVE-2026-4883 is a critical vulnerability in Piotnet Forms, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-434
Which versions are affected by CVE-2026-4883?
How do I fix CVE-2026-4883?
No fix has been published for CVE-2026-4883 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-4883 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4883 exists.
Public exploit code: 1 Nuclei template and 1 proofs of concept on GitHub.
Sources
Also known as GHSA-rpxv-q36f-v8r2.