CVE-2026-5524
CriticalCVSS 9.8Summary
The Divi Form Builder plugin for WordPress up to version 5.1.8 is vulnerable to arbitrary file upload leading to remote code execution. The issue is due to insufficient file extension validation in the do_image_upload() function, where the acceptFileTypes POST parameter is directly interpolated into a regular expression. Attackers can upload files with .phtml, .phar, .php5, or .php7 extensions, bypassing .htaccess protection that only blocks .php files.
Risk Assessment
An unauthenticated attacker can gain full control over the WordPress server by uploading malicious PHP files to the /wp-content/uploads/de_fb_uploads/ directory. On Nginx servers, .htaccess protection is completely ineffective, further increasing the risk.
Recommendation
Immediately update the Divi Form Builder plugin to version 5.1.9 or later. If an update is not possible, temporarily disable the plugin or block access to the /wp-content/uploads/de_fb_uploads/ directory using server rules.
Original NVD description (English source)
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.