CVE-2026-24815: Datavane TIS File Upload Vulnerability

CVE-2026-24815 Overview

CVE-2026-24815 is a critical vulnerability affecting the datavane tis platform, combining two dangerous security weaknesses: Unrestricted Upload of File with Dangerous Type and Deserialization of Untrusted Data. The vulnerability resides in the tis-plugin/src/main/java/com/qlangtech/tis/extension/impl modules, specifically associated with the XmlFile.Java program file. This dual vulnerability allows attackers to potentially upload malicious files and exploit insecure deserialization to achieve remote code execution on affected systems.

Critical Impact

This vulnerability carries a maximum CVSS 4.0 score, enabling unauthenticated remote attackers to potentially achieve full system compromise through unrestricted file upload combined with insecure deserialization.

Affected Products

• datavane tis versions prior to v4.3.0
• tis-plugin module (tis-plugin/src/main/java/com/qlangtech/tis/extension/impl)
• XmlFile.Java component

Discovery Timeline

• 2026-01-27 - CVE-2026-24815 published to NVD
• 2026-01-27 - Last updated in NVD database

Technical Details for CVE-2026-24815

Vulnerability Analysis

This vulnerability represents a severe security flaw combining two distinct but related weaknesses. The Unrestricted Upload of File with Dangerous Type (CWE-434) allows attackers to upload files containing executable content without proper validation or restrictions. When combined with Deserialization of Untrusted Data, attackers can craft malicious serialized objects that, when processed by the vulnerable XmlFile.Java component, lead to arbitrary code execution.

The affected module tis-plugin/src/main/java/com/qlangtech/tis/extension/impl handles plugin extension functionality, making it a high-value target for attackers seeking to inject malicious code into the tis platform. The network-accessible attack vector with no authentication requirements makes this vulnerability particularly dangerous in exposed deployments.

Root Cause

The root cause stems from insufficient validation in the file upload handling mechanism combined with unsafe deserialization practices in the XmlFile.Java component. The application fails to properly restrict the types of files that can be uploaded and does not implement secure deserialization patterns when processing XML data. This allows attackers to upload specially crafted files containing malicious serialized payloads that are subsequently deserialized without adequate security controls.

Attack Vector

The attack can be executed remotely over the network without requiring any prior authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying an exposed tis instance with the vulnerable plugin module
2. Crafting a malicious file containing a serialized payload designed to execute arbitrary code
3. Uploading the malicious file through the unrestricted upload functionality
4. Triggering the deserialization of the malicious payload via the XmlFile.Java component
5. Achieving remote code execution with the privileges of the tis application

The vulnerability mechanism involves the XmlFile.Java component processing uploaded files without proper type validation. When malicious XML content containing serialized Java objects is processed, the insecure deserialization allows attackers to instantiate arbitrary objects and execute code. For technical implementation details, refer to the GitHub Pull Request #443 which addresses this vulnerability.

Detection Methods for CVE-2026-24815

Indicators of Compromise

• Unexpected file uploads to the tis plugin directories, particularly files with unusual extensions or content types
• Unusual process spawning from the tis Java process, especially shell invocations or network connections
• XML files containing suspicious serialized Java object patterns in upload directories
• Abnormal network traffic patterns originating from the tis application server

Detection Strategies

• Monitor file upload endpoints for attempts to upload executable content or files with dangerous MIME types
• Implement deserialization monitoring to detect attempts to instantiate dangerous classes
• Deploy web application firewall (WAF) rules to detect malicious serialized payloads in HTTP requests
• Review access logs for unusual patterns targeting the tis-plugin extension implementation endpoints

Monitoring Recommendations

• Enable verbose logging for the com.qlangtech.tis.extension.impl package to capture file processing events
• Configure alerting for new file creations in plugin directories with non-whitelisted extensions
• Implement runtime application self-protection (RASP) to detect and block deserialization attacks
• Monitor system resource usage for anomalies indicating post-exploitation activity

How to Mitigate CVE-2026-24815

Immediate Actions Required

• Upgrade datavane tis to version v4.3.0 or later immediately
• If immediate upgrade is not possible, restrict network access to the tis instance using firewall rules
• Review and audit any files uploaded to the system prior to patching for signs of compromise
• Implement network segmentation to limit the blast radius of potential exploitation

Patch Information

The vulnerability has been addressed in datavane tis version v4.3.0. The fix is documented in GitHub Pull Request #443. Organizations should upgrade to this version or later to remediate the vulnerability. Review the pull request for specific changes made to the XmlFile.Java component and related modules.

Workarounds

• Implement strict file type validation at the web server or reverse proxy level before requests reach the tis application
• Deploy a Web Application Firewall (WAF) with rules to block serialized Java object patterns and dangerous file uploads
• Restrict access to the tis plugin upload functionality to trusted IP addresses only
• Consider disabling the affected plugin functionality if not critical to operations until patching is complete

# Example: Restrict network access to tis instance using iptables
# Allow only trusted admin network
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP

# Example: Nginx location block to restrict upload endpoints
# Add to nginx configuration for tis reverse proxy
# location ~ /tis-plugin/.*upload {
#     allow 10.0.0.0/24;
#     deny all;
# }