WordPress Plugin: drag-and-drop-multiple-file-upload-contact-form-7: CVE-2026-5710: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to Path Traversal leading to Arbitrary File Read in versions up to and including 1.3.9.6. This is due to the plugin using client-supplied mfile[] POST values as the source of truth for email attachment selection without performing any server-side upload provenance check, path canonicalization, or directory containment boundary enforcement. In dnd_wpcf7_posted_data(), each user-submitted filename is directly appended to the plugin's upload URL without sanitization. In dnd_cf7_mail_components(), the URL is converted back to a filesystem path using str_replace() and only file_exists() is used as the acceptance check before attaching the file to the outgoing CF7 email. This makes it possible for unauthenticated attackers to read and exfiltrate arbitrary files readable by the web server process via path traversal sequences in the mfile[] parameter, with files being disclosed as email attachments. Note: This vulnerability is limited to the 'wp-content' folder due to the wpcf7_is_file_path_in_content_dir() function in the Contact Form 7 plugin.