CVE-2026-1499: WP Duplicate WordPress Plugin RCE Flaw

CVE-2026-1499 Overview

The WP Duplicate plugin for WordPress (also known as Local Sync) contains a critical vulnerability involving missing authorization combined with arbitrary file upload capabilities. This flaw affects all versions up to and including 1.1.8 and allows attackers to achieve remote code execution on vulnerable WordPress installations.

The vulnerability stems from a missing capability check on the process_add_site() AJAX action, combined with path traversal in the file upload functionality. This creates a two-stage attack chain where authenticated attackers with minimal privileges (subscriber-level) can first manipulate internal plugin options, which then enables unauthenticated attackers to bypass authentication checks and upload arbitrary files to the server.

Critical Impact

This vulnerability allows unauthenticated remote code execution through a chained attack involving missing authorization and arbitrary file upload, potentially leading to complete WordPress site compromise.

Affected Products

• WP Duplicate plugin (Local Sync) for WordPress versions up to and including 1.1.8
• WordPress installations with the vulnerable plugin activated
• Sites allowing subscriber-level user registration

Discovery Timeline

• February 6, 2026 - CVE-2026-1499 published to NVD
• February 6, 2026 - Last updated in NVD database

Technical Details for CVE-2026-1499

Vulnerability Analysis

This vulnerability represents a classic example of a chained attack combining multiple weaknesses to achieve critical impact. The attack begins with CWE-862 (Missing Authorization) in the process_add_site() function, which lacks proper capability checks to verify whether the requesting user has administrative privileges.

The process_add_site() AJAX action allows authenticated users with minimal privileges to set the internal prod_key_random_id option. This option serves as an authentication token for subsequent operations. Once this token is manipulated, unauthenticated attackers can exploit the handle_upload_single_big_file() function, which accepts file uploads without proper authorization when the correct token is provided.

The file upload functionality also suffers from path traversal issues, enabling attackers to write files to arbitrary locations on the server. By uploading a malicious PHP file to an accessible web directory, attackers can achieve remote code execution with the privileges of the web server process.

Root Cause

The root cause of this vulnerability is the absence of proper capability checks in the process_add_site() AJAX handler. WordPress provides built-in functions like current_user_can() to verify user capabilities before performing sensitive operations. The vulnerable code fails to implement these checks, allowing any authenticated user (including those with subscriber-level access) to invoke administrative functions.

Additionally, the handle_upload_single_big_file() function relies solely on a token-based authentication mechanism (prod_key_random_id) without verifying that the token was legitimately set by an authorized user. This design flaw enables the bypass of authentication controls when the token value is known or manipulated.

Attack Vector

The attack is network-based and can be executed remotely against any WordPress site running the vulnerable plugin version. The attack chain proceeds as follows:

1. Initial Access: Attacker obtains or creates a subscriber-level account on the target WordPress site (many WordPress sites allow user registration)
2. Token Manipulation: Using the authenticated session, the attacker calls the process_add_site() AJAX endpoint to set a known value for the prod_key_random_id option
3. Authentication Bypass: With knowledge of the token, the attacker can now make unauthenticated requests to the file upload handler
4. Malicious Upload: The attacker uploads a PHP web shell or other malicious payload using the handle_upload_single_big_file() function
5. Code Execution: The uploaded file is accessed via the web server, executing arbitrary code with web server privileges

The vulnerability requires no user interaction and can be exploited with low attack complexity, making it highly dangerous for exposed WordPress installations.

Detection Methods for CVE-2026-1499

Indicators of Compromise

• Unexpected files with .php extension appearing in WordPress directories outside standard plugin/theme locations
• Suspicious POST requests to /wp-admin/admin-ajax.php with action parameters referencing process_add_site or file upload functions
• Modified wp_options database entries for prod_key_random_id with unexpected values
• Web server access logs showing unusual file upload activity to Local Sync plugin endpoints
• New or suspicious subscriber-level user accounts created shortly before exploitation attempts

Detection Strategies

• Monitor WordPress AJAX endpoints for unauthorized calls to process_add_site from non-administrative users
• Implement file integrity monitoring to detect unauthorized file additions or modifications in web directories
• Review web server logs for POST requests containing large file uploads to plugin-specific endpoints
• Deploy web application firewall (WAF) rules to detect and block path traversal patterns in upload requests
• Audit database changes to the wp_options table for unexpected modifications to plugin-related keys

Monitoring Recommendations

• Enable detailed logging for WordPress AJAX actions and review for anomalous patterns
• Implement real-time alerting for new PHP file creation in WordPress directories
• Monitor outbound network connections from the web server that may indicate post-exploitation activity
• Track user privilege changes and new account registrations for potential attack staging

How to Mitigate CVE-2026-1499

Immediate Actions Required

• Update the WP Duplicate (Local Sync) plugin to the latest patched version immediately
• Audit existing WordPress user accounts and remove any suspicious subscriber-level accounts
• Scan the WordPress installation for unauthorized PHP files or web shells
• Review database entries for prod_key_random_id and reset if tampered with
• Consider temporarily disabling the plugin until patching is complete

Patch Information

A security patch has been released addressing this vulnerability. The fix implements proper capability checks in the process_add_site() function and adds appropriate authorization controls to the file upload handler. Site administrators should update to the patched version through the WordPress plugin update mechanism or by downloading directly from the WordPress plugin repository.

For detailed information about the code changes, refer to the WordPress Local Sync Changeset. Additional vulnerability analysis is available from Wordfence.

Workarounds

• Disable new user registration on WordPress sites if not required for business operations
• Implement additional server-level restrictions on file uploads and PHP execution in upload directories
• Use a web application firewall (WAF) with rules to block suspicious AJAX requests and file upload patterns
• Restrict access to wp-admin/admin-ajax.php from untrusted IP addresses if feasible
• Add server-level configuration to prevent PHP execution in directories where uploaded files are stored

# Apache configuration to prevent PHP execution in uploads directory
# Add to .htaccess in wp-content/uploads/
<FilesMatch "\.php$">
    Order Allow,Deny
    Deny from all
</FilesMatch>