CVE-2025-29287: Mingsoft MCMS File Upload RCE Vulnerability

CVE-2025-29287 Overview

An arbitrary file upload vulnerability has been identified in the ueditor component of Mingsoft MCMS v5.4.3. This vulnerability allows remote attackers to upload maliciously crafted files to the server, potentially leading to arbitrary code execution. The ueditor component fails to properly validate uploaded files, enabling attackers to bypass security controls and upload executable content that can compromise the entire web application and underlying server infrastructure.

Critical Impact

Remote attackers can upload malicious files without authentication, potentially achieving full server compromise through arbitrary code execution. This vulnerability poses a significant risk to organizations running affected MCMS installations.

Affected Products

• Mingsoft MCMS version 5.4.3
• MCMS installations utilizing the ueditor component
• Systems running MCMS 5.4.3 with default configurations

Discovery Timeline

• 2025-04-21 - CVE-2025-29287 published to NVD
• 2025-04-24 - Last updated in NVD database

Technical Details for CVE-2025-29287

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The ueditor component in MCMS v5.4.3 contains an arbitrary file upload flaw that stems from insufficient validation of uploaded file types and content. The vulnerability is exploitable over the network without requiring any authentication or user interaction, making it particularly dangerous for internet-facing MCMS deployments.

The attack surface is significant because MCMS is a content management system commonly deployed on web servers, and the ueditor component is a rich text editor that handles file uploads as part of its core functionality.

Root Cause

The root cause of this vulnerability lies in the inadequate file upload validation within the ueditor component. The component fails to properly enforce file type restrictions, allowing attackers to upload files with executable extensions or embed malicious content within seemingly benign file types. This lack of server-side validation enables bypass of any client-side controls that may be present.

Attack Vector

The attack is conducted over the network, targeting the ueditor file upload endpoint. An attacker can craft a malicious file—such as a web shell or script containing executable code—and upload it through the vulnerable component. Once uploaded, the attacker can access the malicious file via the web server, triggering code execution with the privileges of the web application.

The vulnerability mechanism involves sending specially crafted HTTP requests to the ueditor upload handler. The attacker manipulates the file extension, content-type header, or file content to bypass any existing validation. Technical details regarding the specific exploitation methodology can be found in the GitHub Gist CVE-2025-29287 and the Gitee MCMS Issue Discussion.

Detection Methods for CVE-2025-29287

Indicators of Compromise

• Unexpected files with executable extensions (.jsp, .php, .aspx) appearing in upload directories
• Web shell artifacts or suspicious script files in the MCMS content storage paths
• Anomalous HTTP POST requests to ueditor upload endpoints with unusual file content
• Server processes spawned by the web application user executing unexpected commands

Detection Strategies

• Monitor file system activity in MCMS upload directories for creation of executable files
• Implement web application firewall (WAF) rules to detect and block file upload attempts containing executable code patterns
• Review web server access logs for suspicious POST requests targeting /ueditor/ endpoints
• Deploy file integrity monitoring on web application directories to detect unauthorized file additions

Monitoring Recommendations

• Enable verbose logging for the MCMS application and ueditor component
• Set up alerts for new file creation events in upload directories with executable extensions
• Monitor for outbound network connections initiated by the web server process, which may indicate successful exploitation
• Implement regular security scans of the MCMS installation to identify unauthorized files

How to Mitigate CVE-2025-29287

Immediate Actions Required

• Restrict access to the ueditor upload functionality to authenticated and authorized users only
• Implement strict server-side file type validation that inspects file content, not just extensions
• Consider disabling the ueditor component temporarily if file upload functionality is not required
• Apply network-level access controls to limit exposure of the MCMS application

Patch Information

Organizations should monitor the Mingsoft MCMS project for security updates and apply patches as soon as they become available. Review the Gitee MCMS Issue Discussion for the latest information regarding remediation efforts from the vendor.

Workarounds

• Configure the web server to prevent execution of files in upload directories by removing execute permissions
• Implement a whitelist of allowed file extensions at the server level, blocking all executable types
• Use a reverse proxy or WAF to filter malicious upload attempts before they reach the application
• Relocate uploaded files to a separate storage location outside the web root to prevent direct access

# Example: Disable script execution in upload directories (Apache)
<Directory "/path/to/mcms/upload">
    Options -ExecCGI
    AddHandler cgi-script .php .jsp .aspx .exe
    RemoveHandler .php .jsp .aspx
    php_flag engine off
</Directory>