Bricksforge WordPress Plugin Arbitrary File Upload Vulnerability

The Bricksforge plugin for WordPress is vulnerable to an unauthenticated arbitrary file upload vulnerability in versions up to and including 3.1.8.9.

The flaw stems from insufficient validation of the attacker-controlled URL field in the temporaryFileUploads parameter during form submission. An attacker can:

• Obtain a valid nonce via the bricksforge_regenerate_nonce AJAX endpoint.
• Upload a GIF/PHP polyglot file to the temporary upload directory, where MIME type validation is correctly performed.
• Submit a form with a crafted temporaryFileUploads parameter where the server-side file path points to the validated GIF file, but the attacker-controlled URL field ends with a .php extension.

This allows unauthenticated attackers to upload and execute arbitrary PHP code on the server.