CVE-2026-2684: Tsinghua Unigroup RCE Vulnerability

CVE-2026-2684 Overview

A vulnerability has been identified in Tsinghua Unigroup Electronic Archives System up to version 3.2.210802(62532). The vulnerability exists in the file upload functionality located at /Archive/ErecordManage/uploadFile.html. By manipulating the File argument, an attacker can achieve unrestricted file upload, potentially leading to remote code execution or other malicious activities. The attack can be launched remotely without authentication, making it a significant security concern for organizations using this system. The exploit has been publicly disclosed, and the vendor was contacted about this issue but did not respond.

Critical Impact

Unrestricted file upload vulnerability allows remote attackers to upload malicious files to the server, potentially leading to remote code execution, web shell deployment, or system compromise.

Affected Products

• Tsinghua Unigroup Electronic Archives System up to version 3.2.210802(62532)
• /Archive/ErecordManage/uploadFile.html file upload endpoint

Discovery Timeline

• 2026-02-19 - CVE CVE-2026-2684 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-2684

Vulnerability Analysis

This vulnerability is classified under CWE-284 (Improper Access Control), indicating that the affected file upload functionality lacks proper security controls to restrict the types of files that can be uploaded. The unrestricted file upload vulnerability in the Tsinghua Unigroup Electronic Archives System stems from insufficient validation of user-supplied file uploads through the uploadFile.html endpoint.

When a user uploads a file via the vulnerable endpoint, the application fails to properly validate or restrict the file type, content, or extension. This allows an attacker to upload arbitrary files, including executable scripts such as web shells, which can then be accessed and executed on the server. The vulnerability can be exploited remotely over the network, requiring no prior authentication or special privileges, making it accessible to any attacker with network access to the vulnerable system.

Root Cause

The root cause of this vulnerability is improper access control and missing input validation on the file upload functionality. The application does not implement adequate security measures to:

1. Validate file extensions against a whitelist of allowed types
2. Verify file content matches the declared file type (MIME type validation)
3. Restrict upload permissions to authenticated users
4. Sanitize filenames to prevent path traversal attacks
5. Store uploaded files outside the web-accessible directory

Attack Vector

The vulnerability is exploited through the network by sending a crafted HTTP request to the /Archive/ErecordManage/uploadFile.html endpoint. An attacker manipulates the File parameter to upload malicious content such as web shells or executable scripts. Once uploaded, the attacker can access the file directly on the web server to execute arbitrary commands.

The attack flow typically involves:

1. Identifying the vulnerable endpoint at /Archive/ErecordManage/uploadFile.html
2. Crafting a multipart form request with a malicious file (e.g., PHP/JSP web shell)
3. Uploading the file without authentication
4. Accessing the uploaded file to achieve code execution on the server

Technical details and proof-of-concept information are available at the GitHub PoC Repository and the PoC Introduction page.

Detection Methods for CVE-2026-2684

Indicators of Compromise

• Unexpected files appearing in upload directories, particularly with executable extensions (.php, .jsp, .aspx, .sh)
• HTTP POST requests to /Archive/ErecordManage/uploadFile.html from external or unauthorized IP addresses
• Suspicious process spawning from the web server process after file uploads
• Web shell signatures or known malicious file hashes in upload directories

Detection Strategies

• Monitor HTTP traffic for POST requests to /Archive/ErecordManage/uploadFile.html and analyze uploaded file content
• Implement file integrity monitoring on web server directories to detect unauthorized file creation
• Deploy web application firewall (WAF) rules to inspect and block malicious file uploads
• Analyze server logs for unusual file upload patterns or requests from suspicious IP addresses

Monitoring Recommendations

• Enable verbose logging on the Electronic Archives System to capture all file upload activities
• Configure alerts for file uploads containing executable content or suspicious extensions
• Monitor outbound network connections from the web server that may indicate command-and-control communication
• Regularly scan upload directories for known web shell signatures and malicious file indicators

How to Mitigate CVE-2026-2684

Immediate Actions Required

• Restrict network access to the Electronic Archives System to trusted IP addresses only
• Disable or remove the vulnerable /Archive/ErecordManage/uploadFile.html endpoint if not required for business operations
• Implement a web application firewall (WAF) with rules to block malicious file uploads
• Conduct a security audit of all uploaded files to identify and remove any existing malicious content
• Monitor the system for indicators of compromise while awaiting a vendor patch

Patch Information

As of the last update, the vendor (Tsinghua Unigroup) was contacted about this vulnerability but did not respond. No official patch is currently available. Organizations should implement the workarounds described below and monitor for vendor updates. Additional vulnerability details can be found at VulDB Entry #346475.

Workarounds

• Implement strict file type validation using an allowlist approach, permitting only known safe file types
• Configure the web server to prevent execution of uploaded files by storing them outside the web root
• Deploy network segmentation to isolate the vulnerable system from critical infrastructure
• Require authentication for all file upload operations and implement role-based access controls
• Use endpoint detection and response (EDR) solutions like SentinelOne to detect and block malicious file execution

# Example: Apache configuration to block script execution in upload directories
<Directory "/path/to/upload/directory">
    # Disable script execution
    Options -ExecCGI -Indexes
    
    # Prevent PHP execution
    php_admin_flag engine off
    
    # Deny access to executable extensions
    <FilesMatch "\.(php|jsp|aspx|cgi|pl|py|sh|exe)$">
        Require all denied
    </FilesMatch>
</Directory>