Drag and Drop Multiple File Upload for Contact Form 7 <= 1.3.8.9 - Unauthenticated Arbitrary File Upload via Insufficient Blacklist Checks

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to arbitrary file uploads due to insufficient file type validation in all versions up to, and including, 1.3.8.9. This makes it possible for unauthenticated attackers to bypass the plugin's blacklist and upload .phar or other dangerous file types on the affected site's server, which may make remote code execution possible on the servers that are configured to handle .phar files as executable PHP scripts, particularly in default Apache+mod_php configurations where the file extension is not strictly validated before being passed to the PHP interpreter.

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Drag and Drop Multiple File Upload for Contact Form 7 1.3.9.0 closes this, and updating the plugin is the step that ends it.

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