CVE-2025-12674: KiotViet Sync WordPress RCE Vulnerability

CVE-2025-12674 Overview

The KiotViet Sync plugin for WordPress contains a critical arbitrary file upload vulnerability due to missing file type validation in the create_media() function. This security flaw affects all versions up to and including 1.8.5, allowing unauthenticated attackers to upload arbitrary files to the affected site's server, potentially leading to remote code execution.

Critical Impact

Unauthenticated attackers can upload malicious files including PHP webshells, enabling complete server compromise and remote code execution without any authentication required.

Affected Products

• KiotViet Sync WordPress Plugin versions ≤ 1.8.5
• WordPress sites with KiotViet Sync plugin installed
• Web servers hosting vulnerable WordPress installations

Discovery Timeline

• 2025-11-05 - CVE-2025-12674 published to NVD
• 2025-11-06 - Last updated in NVD database

Technical Details for CVE-2025-12674

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The root cause lies in the create_media() function within the KiotViet Sync plugin, which fails to implement proper file type validation before accepting uploaded files. This architectural oversight allows attackers to bypass intended security controls and upload executable files directly to the WordPress server.

The vulnerability is particularly severe because it requires no authentication to exploit. An attacker can directly interact with the vulnerable endpoint and submit malicious payloads without needing valid credentials or user interaction. Once a malicious file such as a PHP webshell is uploaded, the attacker can execute arbitrary commands on the server with the privileges of the web server process.

Root Cause

The create_media() function in the KiotViet Sync plugin lacks essential security controls for validating uploaded file types. Proper implementation should include MIME type verification, file extension whitelisting, and content inspection to ensure only expected file types (such as images) are accepted. The absence of these validation mechanisms creates a direct path for attackers to upload executable code.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can craft a malicious HTTP request to the vulnerable create_media() endpoint, submitting a PHP webshell or other malicious payload disguised as a legitimate file upload. The server accepts the file without validation, storing it in a web-accessible location. The attacker then accesses the uploaded file directly via URL to execute arbitrary commands on the server.

The exploitation flow typically involves:

1. Identifying a WordPress site running the vulnerable KiotViet Sync plugin
2. Crafting a multipart HTTP POST request with a malicious PHP file
3. Sending the request to the create_media() endpoint
4. Accessing the uploaded file to trigger code execution
5. Establishing persistent access or exfiltrating sensitive data

Detection Methods for CVE-2025-12674

Indicators of Compromise

• Unexpected PHP files in WordPress upload directories (wp-content/uploads/)
• Web server logs showing POST requests to KiotViet Sync endpoints with unusual file extensions
• New or modified files with suspicious names or obfuscated PHP code in upload directories
• Outbound network connections from the web server process to unknown external hosts

Detection Strategies

• Monitor file system changes in WordPress upload directories for newly created PHP or executable files
• Implement web application firewall (WAF) rules to block requests containing PHP code in file upload parameters
• Review web server access logs for POST requests to the KiotViet Sync plugin endpoints followed by GET requests to upload directories
• Deploy file integrity monitoring on WordPress installations to detect unauthorized file additions

Monitoring Recommendations

• Enable detailed logging for WordPress plugin activity and file upload operations
• Configure alerting for any new executable files created in web-accessible directories
• Monitor for web shells and backdoors using endpoint detection and response (EDR) solutions
• Regularly audit installed plugins and their versions against known vulnerability databases

How to Mitigate CVE-2025-12674

Immediate Actions Required

• Immediately update the KiotViet Sync plugin to a patched version if available
• If no patch is available, deactivate and remove the KiotViet Sync plugin until a fix is released
• Audit WordPress upload directories for any suspicious or unauthorized files
• Review web server logs for signs of exploitation attempts
• Consider implementing a web application firewall (WAF) to block malicious upload attempts

Patch Information

Users should check the WordPress Plugin Directory for updated versions of the KiotViet Sync plugin that address this vulnerability. Additional details about the vulnerability can be found in the Wordfence Vulnerability Report.

Workarounds

• Disable the KiotViet Sync plugin until a patched version is available
• Implement server-level restrictions to prevent PHP execution in upload directories
• Add .htaccess rules or web server configuration to block access to potentially malicious file types in upload directories
• Deploy a web application firewall with rules to inspect and block malicious file uploads
• Restrict access to WordPress admin and plugin endpoints using IP whitelisting where possible

# Apache .htaccess configuration to prevent PHP execution in uploads directory
# Add to wp-content/uploads/.htaccess
<FilesMatch "\.(?i:php|php3|php4|php5|phtml|phar)$">
    Order Deny,Allow
    Deny from all
</FilesMatch>