CVE-2025-56815: Datart Path Traversal Vulnerability

CVE-2025-56815 Overview

CVE-2025-56815 is a Directory Traversal vulnerability affecting Datart version 1.0.0-rc.3, an open-source data visualization and analytics platform developed by Running-elephant. The vulnerability exists in the POST /viz/image interface where the server directly uses MultipartFile.transferTo() to save uploaded files to a path controllable by the user without proper validation of the file name. This allows attackers to write arbitrary files to locations outside the intended directory structure.

Critical Impact

Attackers can exploit this vulnerability to upload malicious files to arbitrary locations on the server, potentially leading to sensitive data exposure, configuration tampering, or establishing persistence mechanisms for further attacks.

Affected Products

• Running-elephant Datart 1.0.0-rc.3
• Datart visualization platform with exposed /viz/image endpoint

Discovery Timeline

• 2025-09-24 - CVE-2025-56815 published to NVD
• 2025-10-10 - Last updated in NVD database

Technical Details for CVE-2025-56815

Vulnerability Analysis

This Directory Traversal vulnerability stems from improper handling of file uploads in the Datart visualization platform. The vulnerable endpoint at /viz/image accepts multipart file uploads and processes them using the Spring Framework's MultipartFile.transferTo() method. The critical flaw lies in the application's failure to sanitize or validate the filename parameter before using it to construct the destination file path.

When a user submits a file upload request, the application constructs the save path by concatenating a base directory with the user-supplied filename. Without proper validation, an attacker can craft a malicious filename containing path traversal sequences (such as ../) to escape the intended upload directory and write files to arbitrary locations on the filesystem. This attack requires user interaction, as the request must be crafted and submitted, but requires no authentication to exploit.

Root Cause

The root cause of CVE-2025-56815 is the direct use of user-controlled input when determining the file save location. The MultipartFile.transferTo() method in Spring accepts a destination path and writes the file contents to that location. When the application fails to:

1. Validate that the filename contains only permitted characters
2. Remove or reject path traversal sequences (../, ..\\)
3. Canonicalize the path and verify it remains within the allowed directory

An attacker can exploit this oversight to traverse the directory structure and write files to sensitive locations on the server.

Attack Vector

The attack is executed over the network by sending a crafted HTTP POST request to the /viz/image endpoint. The attacker manipulates the filename field in the multipart form data to include directory traversal sequences. For example, a filename like ../../../etc/cron.d/malicious could potentially write a file to the system's cron directory on a Linux server.

The exploitation mechanism involves crafting a multipart/form-data request where the filename parameter contains path traversal sequences combined with a target path. When the server processes this request, it attempts to save the uploaded file to the attacker-controlled location. The impact includes potential file overwrites, configuration manipulation, and in some scenarios, remote code execution if the attacker can write to locations where executable content is processed.

For detailed technical information and proof-of-concept details, refer to the CVE-2025-56815 GitHub repository.

Detection Methods for CVE-2025-56815

Indicators of Compromise

• HTTP POST requests to /viz/image endpoint containing path traversal sequences (../, ..%2f, ..\\) in filename parameters
• Unexpected files appearing outside the designated upload directories on Datart servers
• Web server logs showing encoded traversal attempts such as %2e%2e%2f or %2e%2e/
• Modified configuration files or new files in system directories that correlate with upload activity

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in file upload requests
• Monitor HTTP request logs for /viz/image endpoints with suspicious filename parameters containing .. sequences
• Deploy file integrity monitoring (FIM) on critical system directories to detect unauthorized file creation or modification
• Analyze multipart form data in web traffic for encoded path traversal attempts

Monitoring Recommendations

• Enable detailed logging for the Datart application, particularly for file upload operations
• Configure SIEM rules to alert on path traversal patterns in HTTP request parameters
• Implement anomaly detection for file system write operations outside expected application directories
• Regularly audit the Datart server filesystem for unexpected files in sensitive locations

How to Mitigate CVE-2025-56815

Immediate Actions Required

• Restrict network access to the /viz/image endpoint using firewall rules or reverse proxy configurations
• Implement input validation at the web server or WAF level to reject filenames containing path traversal sequences
• Review and remove any unauthorized files that may have been written to the server filesystem
• Consider temporarily disabling the image upload functionality until a patch is applied

Patch Information

At the time of writing, users should monitor the Datart GitHub repository for security updates and newer releases that address this vulnerability. Organizations running Datart 1.0.0-rc.3 should upgrade to a patched version as soon as one becomes available from Running-elephant.

Workarounds

• Deploy a reverse proxy or WAF rule to sanitize filenames and reject requests containing path traversal patterns
• Implement application-level input validation to normalize filenames and strip directory components before file operations
• Run the Datart application with minimal filesystem permissions to limit the impact of directory traversal attacks
• Isolate the Datart server in a network segment with restricted access to sensitive systems

# Example nginx configuration to block path traversal attempts
location /viz/image {
    # Block requests with path traversal sequences
    if ($request_uri ~* "\.\.") {
        return 403;
    }
    
    # Additional security headers
    add_header X-Content-Type-Options nosniff;
    
    proxy_pass http://datart_backend;
}