CVE-2026-5710: WordPress CF7 Path Traversal Vulnerability

CVE-2026-5710 Overview

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress contains a Path Traversal vulnerability that enables Arbitrary File Read in versions up to and including 1.3.9.6. This vulnerability stems from 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.

The flaw allows unauthenticated attackers to read and exfiltrate arbitrary files readable by the web server process via path traversal sequences in the mfile[] parameter, with sensitive files being disclosed as email attachments. While the vulnerability impact is partially mitigated by the wpcf7_is_file_path_in_content_dir() function in Contact Form 7 which limits file access to the wp-content folder, significant sensitive data can still be exposed.

Critical Impact

Unauthenticated attackers can exfiltrate sensitive files from the WordPress wp-content directory, potentially exposing configuration files, database backups, debug logs, and other sensitive data through email attachments.

Affected Products

• Drag and Drop Multiple File Upload for Contact Form 7 plugin versions up to and including 1.3.9.6
• WordPress installations using the affected plugin with Contact Form 7

Discovery Timeline

• 2026-04-17 - CVE-2026-5710 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-5710

Vulnerability Analysis

This Path Traversal vulnerability (CWE-22) exists because the plugin fails to properly validate and sanitize user-supplied file paths in the email attachment functionality. The attack is network-based and requires no authentication or user interaction, making it particularly dangerous for internet-facing WordPress installations.

In the dnd_wpcf7_posted_data() function, each user-submitted filename from the mfile[] POST parameter is directly appended to the plugin's upload URL without any sanitization or validation. Subsequently, in dnd_cf7_mail_components(), the URL is converted back to a filesystem path using a simple str_replace() operation. The only validation performed is a file_exists() check before attaching the file to the outgoing Contact Form 7 email.

This lack of proper input validation allows attackers to craft malicious requests containing path traversal sequences (such as ../) to access files outside the intended upload directory. The vulnerability enables information disclosure with high confidentiality impact, though it does not affect system integrity or availability.

Root Cause

The root cause is the absence of proper security controls in the file attachment workflow:

1. Missing Input Sanitization: User-supplied mfile[] values are used directly without removing or blocking path traversal sequences
2. No Path Canonicalization: The plugin does not resolve the canonical path to verify the target file location
3. Insufficient Boundary Enforcement: No validation ensures files are within the intended upload directory
4. Trust in Client Data: The plugin treats client-supplied filenames as trusted input without server-side verification

The vulnerable code flow can be traced through the plugin's source files at lines 203, 477, and 718 in dnd-upload-cf7.php, where the unsanitized path handling occurs.

Attack Vector

The attack leverages the network-accessible Contact Form 7 submission endpoint. An attacker can exploit this vulnerability by:

1. Identifying a WordPress site with the vulnerable plugin and a Contact Form 7 form configured for file uploads
2. Crafting a malicious POST request to the form submission endpoint
3. Including path traversal sequences in the mfile[] parameter to reference files outside the upload directory
4. Submitting the form with an attacker-controlled email recipient address
5. Receiving the exfiltrated file contents as email attachments

The exploitation does not require authentication, as Contact Form 7 forms are typically publicly accessible. The attack is limited to files within the wp-content directory due to Contact Form 7's built-in wpcf7_is_file_path_in_content_dir() validation, but this still exposes a significant attack surface including potential database backups, configuration files, and debug logs.

For technical details on the vulnerable code paths, see the WordPress Plugin Code Snippets and the Wordfence Vulnerability Report.

Detection Methods for CVE-2026-5710

Indicators of Compromise

• Unusual Contact Form 7 submissions containing path traversal sequences (../, ..%2f, %2e%2e/) in POST data
• Form submissions with suspicious mfile[] parameter values referencing files outside upload directories
• Email delivery logs showing attachments of unexpected file types or sizes
• Web server access logs showing repeated form submissions to Contact Form 7 endpoints with encoded path characters

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block path traversal patterns in POST parameters
• Monitor for Contact Form 7 form submissions containing ../ or URL-encoded equivalents in file-related parameters
• Review email server logs for outbound messages with unexpected attachment types (e.g., .php, .sql, .log files)
• Audit web server access logs for high-frequency form submissions from single IP addresses

Monitoring Recommendations

• Enable detailed logging for Contact Form 7 submissions and email attachments
• Set up alerts for email attachments containing sensitive file extensions from WordPress forms
• Implement intrusion detection rules to flag path traversal attempts in HTTP POST data
• Regularly review web server error logs for file access attempts outside normal directories

How to Mitigate CVE-2026-5710

Immediate Actions Required

• Update the Drag and Drop Multiple File Upload for Contact Form 7 plugin to the latest patched version immediately
• Audit recent Contact Form 7 submissions for any evidence of exploitation attempts
• Review email logs for any suspicious attachments that may indicate data exfiltration
• Consider temporarily disabling file upload functionality on forms until the patch is applied

Patch Information

A security patch addressing this vulnerability is available through the WordPress Plugin Changeset. Site administrators should update the plugin to the latest available version through the WordPress admin dashboard or by manually downloading the updated plugin files.

The patch implements proper path canonicalization and directory boundary enforcement to prevent traversal attacks. After updating, verify the plugin version in WordPress admin under Plugins to confirm the update was successful.

Workarounds

• Temporarily disable the Drag and Drop Multiple File Upload for Contact Form 7 plugin until the patch can be applied
• Implement WAF rules to block requests containing path traversal patterns (../, ..%2f, %2e%2e%2f) in POST parameters
• Remove sensitive files from the wp-content directory, including database backups, debug logs, and configuration exports
• Consider restricting Contact Form 7 file upload functionality to authenticated users only

# Apache .htaccess rule to block path traversal attempts
# Add to WordPress root .htaccess file
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{QUERY_STRING} (\.\./|\.\.%2f|%2e%2e/) [NC,OR]
RewriteCond %{REQUEST_BODY} (\.\./|\.\.%2f|%2e%2e/) [NC]
RewriteRule .* - [F,L]
</IfModule>