CVE-2026-5524 PoC — Divi Form Builder <= 5.1.8 - Unauthenticated Arbitrary File Upload Leading to Remote Code Execution via 'acceptFileTypes

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-5524.yaml

Associated Vulnerability

Title: Divi Form Builder <= 5.1.8 - Unauthenticated Arbitrary File Upload Leading to Remote Code Execution via 'acceptFileTypes' Parameter (CVE-2026-5524)
Description:The Divi Form Builder plugin for WordPress is vulnerable to Arbitrary File Upload leading to Remote Code Execution in all versions up to and including 5.1.8. This is due to insufficient file extension validation in the do_image_upload() function where user-supplied input from the acceptFileTypes POST parameter is directly interpolated into a regular expression used to validate uploaded files. Attackers can specify PHP-executable extensions such as .phtml, .phar, .php5, or .php7 to bypass the plugin's .htaccess protection which only blocks .php files specifically. Additionally, on Nginx-based servers, the .htaccess protection is completely ineffective as Nginx does not process .htaccess files. This makes it possible for unauthenticated attackers (who can obtain a nonce from any public page containing a form) to upload executable PHP files to the publicly accessible /wp-content/uploads/de_fb_uploads/ directory and achieve Remote Code Execution by accessing the uploaded file via HTTP. The vulnerability was partially patched in version 5.1.3.

Description

The Divi Form Builder plugin for WordPress versions 5.1.8 and prior contains an unauthenticated arbitrary file upload vulnerability in the do_image_upload() AJAX handler. The user-controlled acceptFileTypes POST parameter is injected unsanitized into a PHP regex for file extension validation. By supplying acceptFileTypes=phtml the constructed regex accepts .phtml files while the plugin's .htaccess only blocks .php, so Apache executes .phtml files as PHP. The required nonce (fb_nonce) is publicly embedded in any page containing a Divi form via the de_fb_obj JavaScript object. Uploaded shells land in /wp-content/uploads/de_fb_uploads/. Fixed in 5.1.9.

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