CVE-2026-4883

CRITICAL

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

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-4883. PoCs published by xShadow-Here.

AI-analyzed exploit summary This repository contains a functional exploit for CVE-2026-4883, an unauthenticated arbitrary file upload vulnerability in Piotnet Forms Pro <= 2.1.40. The exploit leverages an incomplete extension blacklist to upload a malicious PHP shell (e.g., .phtml) and achieve remote code execution (RCE).

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.

Exploits (1)

nomisec WORKING POC
by xShadow-Here · poc
https://github.com/xShadow-Here/CVE-2026-4883

This repository contains a functional exploit for CVE-2026-4883, an unauthenticated arbitrary file upload vulnerability in Piotnet Forms Pro <= 2.1.40. The exploit leverages an incomplete extension blacklist to upload a malicious PHP shell (e.g., .phtml) and achieve remote code execution (RCE).

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Piotnet Forms Pro <= 2.1.40
No auth needed
Prerequisites: Target running Piotnet Forms Pro <= 2.1.40 · Access to the WordPress AJAX endpoint
devstral-2 · analyzed Jun 09, 2026 Full analysis →

Scores

CVSS v3 9.8
EPSS 0.0020
EPSS Percentile 41.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-434
Status published
Products (1)
Piotnet/Piotnet Forms < 2.1.40
Published May 19, 2026
Tracked Since May 19, 2026