CVE-2025-56816: Datart Path Traversal Vulnerability

CVE-2025-56816 Overview

CVE-2025-56816 is a critical vulnerability affecting Datart 1.0.0-rc.3 that combines Directory Traversal (CWE-22) with insecure YAML deserialization to enable remote code execution. The vulnerability exists in the configuration file handling mechanism of the application, which allows attackers to upload arbitrary YAML files to the config/jdbc-driver-ext.yml path. The application then parses this file using SnakeYAML's unsafe load() or loadAs() method without proper input sanitization, allowing deserialization of attacker-controlled YAML content.

Critical Impact

Successful exploitation of this vulnerability allows attackers to upload malicious YAML configuration files and achieve arbitrary class instantiation, potentially leading to remote code execution on the affected Datart server.

Affected Products

• Running-elephant Datart 1.0.0-rc3
• Datart installations using the default JDBC driver extension configuration path
• Systems with network-accessible Datart instances without proper access controls

Discovery Timeline

• September 24, 2025 - CVE-2025-56816 published to NVD
• October 10, 2025 - Last updated in NVD database

Technical Details for CVE-2025-56816

Vulnerability Analysis

This vulnerability exploits a dangerous combination of two security weaknesses in the Datart data visualization platform. First, the application fails to properly validate file paths when handling configuration file uploads, enabling directory traversal attacks. Second, when processing the uploaded YAML configuration files, Datart uses SnakeYAML's load() or loadAs() methods which are known to be unsafe when processing untrusted input.

SnakeYAML's default deserialization behavior allows instantiation of arbitrary Java classes specified in the YAML content. When an attacker combines the directory traversal flaw to place a malicious YAML file at config/jdbc-driver-ext.yml, the application will deserialize the attacker-controlled content, instantiating arbitrary classes. This can be leveraged to execute arbitrary code on the server by specifying classes that have dangerous side effects during construction or that can be chained together in a gadget chain.

Root Cause

The root cause of this vulnerability is twofold: insufficient input validation on file upload paths allowing directory traversal, and the use of SnakeYAML's unsafe deserialization methods (load() or loadAs()) without restricting the types of objects that can be instantiated. The application does not implement path canonicalization, path traversal filtering, or SnakeYAML's SafeConstructor to limit deserialization to safe types.

Attack Vector

The attack is network-accessible and requires user interaction to trigger. An attacker can craft a malicious YAML file containing Java object instantiation instructions and upload it to the target path using directory traversal sequences. When the application processes the configuration file, the malicious YAML is deserialized, causing arbitrary class instantiation. Depending on the classes available in the application's classpath, this can be escalated to full remote code execution through gadget chains commonly found in Java applications.

The attack leverages the YAML deserialization mechanism where specially crafted YAML content can specify Java types to instantiate. For example, an attacker could include YAML tags that reference dangerous classes like javax.script.ScriptEngineManager or leverage common gadget chains from libraries present in the application. The uploaded file overwrites the legitimate jdbc-driver-ext.yml configuration, which is then parsed by the application during normal operation.

Detection Methods for CVE-2025-56816

Indicators of Compromise

• Suspicious HTTP requests containing directory traversal sequences (e.g., ../, ..%2f) targeting configuration upload endpoints
• Unexpected modifications to config/jdbc-driver-ext.yml or other configuration files
• YAML files containing suspicious Java class references such as !!javax.script.ScriptEngineManager or !!java.lang.Runtime
• Anomalous process spawning from the Datart application server process

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block directory traversal patterns in requests to Datart endpoints
• Monitor file integrity of the config/ directory for unauthorized changes to YAML configuration files
• Analyze application logs for failed or successful configuration file uploads with path traversal indicators
• Deploy runtime application self-protection (RASP) solutions to detect unsafe deserialization attempts

Monitoring Recommendations

• Enable detailed logging for all file upload operations within the Datart application
• Configure alerts for any file modifications within the application's configuration directories
• Monitor system process trees for unexpected child processes spawned by the Java runtime running Datart
• Implement network traffic analysis to detect potential command and control communications following exploitation

How to Mitigate CVE-2025-56816

Immediate Actions Required

• Restrict network access to Datart instances to trusted users and networks only until a patch is available
• Implement strict file upload validation that canonicalizes paths and rejects any traversal sequences
• Review and harden file permissions on the Datart configuration directory to prevent unauthorized writes
• Consider deploying a reverse proxy with request inspection to filter malicious payloads

Patch Information

As of the last update on October 10, 2025, no official patch information has been released by the vendor. Organizations should monitor the Datart GitHub repository for security updates and new releases that address this vulnerability. In the meantime, apply the recommended workarounds to reduce exposure.

Workarounds

• Modify the SnakeYAML configuration to use SafeConstructor instead of the default constructor, which restricts deserialization to safe Java types only
• Implement input validation that canonicalizes file paths and explicitly blocks directory traversal sequences before processing uploads
• Deploy network segmentation to isolate Datart instances from untrusted network zones
• Enable application-level authentication and authorization controls to restrict access to configuration management features

# Example: Set restrictive permissions on Datart config directory
chmod 750 /path/to/datart/config
chown datart:datart /path/to/datart/config
# Remove write permissions for the application user if config changes are not needed
chmod 550 /path/to/datart/config