Attack Chain

1. An unauthenticated attacker identifies a WordPress site using the vulnerable "Drag and Drop Multiple File Upload for Contact Form 7" plugin.
2. The attacker crafts a malicious HTTP POST request to a Contact Form 7 endpoint on the WordPress site.
3. The POST request includes a mfile[] parameter containing a path traversal sequence (e.g., ../../../../wp-config.php).
4. The dnd_wpcf7_posted_data() function processes the mfile[] value without sanitization, appending the user-supplied filename to the plugin's upload URL.
5. The dnd_cf7_mail_components() function converts the URL to a filesystem path using str_replace().
6. The file_exists() function is used as a check, but the path traversal allows access to files outside the intended directory.
7. The targeted file (e.g., wp-config.php) is attached to an outgoing Contact Form 7 email as an attachment.
8. The attacker retrieves the email (if possible) or monitors for successful email transmission, gaining access to the contents of the targeted file.

Impact

Successful exploitation of this path traversal vulnerability allows unauthenticated attackers to read arbitrary files within the 'wp-content' directory that are accessible to the web server process. This may include sensitive configuration files (e.g., wp-config.php containing database credentials), plugin code, and uploaded media. The impact is limited to the 'wp-content' directory due to the wpcf7_is_file_path_in_content_dir() function within the Contact Form 7 plugin which performs a check to ensure that the requested file is within that folder.

Recommendation

• Upgrade the "Drag and Drop Multiple File Upload for Contact Form 7" plugin to a version higher than 1.3.9.6 to patch CVE-2026-5710.
• Deploy the provided Sigma rule Detect WordPress Drag and Drop Plugin Path Traversal to identify attempts to exploit this vulnerability via HTTP requests.
• Monitor web server logs for suspicious requests containing path traversal sequences (e.g., ../, ..%2f) in the mfile[] parameter to detect exploitation attempts.