CVE-2026-40899: DataEase JDBC Blocklist Bypass Vulnerability

CVE-2026-40899 Overview

CVE-2026-40899 is a JDBC parameter blocklist bypass vulnerability affecting DataEase, an open-source data visualization and analytics platform. The vulnerability exists in the MySQL datasource configuration component where an attacker can bypass security restrictions designed to block dangerous JDBC parameters. By exploiting Lombok's auto-generated setter methods during Jackson deserialization, an authenticated attacker can replace the security blocklist with an empty list, enabling the use of malicious JDBC parameters such as allowLoadLocalInfile=true. This can lead to arbitrary file read from the server filesystem when combined with a rogue MySQL server.

Critical Impact

Authenticated attackers can read arbitrary files from the DataEase server filesystem, including sensitive environment variables, database credentials, and configuration files by exploiting the LOAD DATA LOCAL INFILE protocol feature.

Affected Products

• DataEase versions 2.10.20 and below
• DataEase MySQL datasource configurations
• Systems using Lombok @Data annotation with Jackson deserialization

Discovery Timeline

• April 16, 2026 - CVE CVE-2026-40899 published to NVD
• April 16, 2026 - Last updated in NVD database

Technical Details for CVE-2026-40899

Vulnerability Analysis

This vulnerability stems from an insecure interaction between Lombok's @Data annotation and Jackson JSON deserialization in the DataEase MySQL datasource configuration. The Mysql class uses Lombok's @Data annotation, which automatically generates public getter and setter methods for all fields, including the illegalParameters field that contains the JDBC security blocklist.

When a datasource configuration is submitted as JSON, Jackson's deserialization process calls the auto-generated setIllegalParameters() method with an attacker-controlled value. By supplying an empty list for this field, the attacker effectively clears the security blocklist before the getJdbc() validation runs. This represents CWE-183: Permissive List of Allowed Inputs, where the security mechanism can be completely bypassed.

The exploitation chain continues by configuring a datasource that points to an attacker-controlled rogue MySQL server with the dangerous parameter allowLoadLocalInfile=true now permitted. The rogue server can then exploit MySQL's LOAD DATA LOCAL INFILE protocol feature to request arbitrary files from the DataEase server, leading to sensitive information disclosure.

Root Cause

The root cause is the use of Lombok's @Data annotation on the Mysql class, which auto-generates a public setter method for the illegalParameters field. This field is designed to contain a blocklist of dangerous JDBC parameters that should be rejected during datasource configuration. However, since Jackson deserialization calls all available setters when parsing JSON input, an attacker can supply their own value for illegalParameters (such as an empty list) before the validation logic in getJdbc() executes. This design flaw allows the security blocklist to be replaced at deserialization time, completely bypassing the intended security control.

Attack Vector

The attack requires network access and low-privilege authentication to the DataEase platform. The attacker submits a malicious datasource configuration as JSON that includes an empty illegalParameters array. During Jackson deserialization, the security blocklist is replaced with the attacker's empty list. The attacker then configures the datasource connection to point to a rogue MySQL server they control, including the now-permitted allowLoadLocalInfile=true parameter. When DataEase connects to the rogue server, the attacker exploits the LOAD DATA LOCAL INFILE protocol to exfiltrate files from the DataEase server filesystem, potentially including /etc/passwd, environment variable files, database credentials, and application configuration files.

Detection Methods for CVE-2026-40899

Indicators of Compromise

• Datasource configurations with empty or modified illegalParameters fields in JSON requests
• Outbound MySQL connections to unknown or suspicious external IP addresses
• Datasource configurations containing allowLoadLocalInfile=true or similar dangerous JDBC parameters
• Unexpected file access patterns on the DataEase server correlating with MySQL datasource connections

Detection Strategies

• Monitor datasource configuration API endpoints for JSON payloads containing illegalParameters fields with empty arrays or attacker-controlled values
• Implement network monitoring for MySQL connections (port 3306) to external or unauthorized IP addresses
• Audit application logs for datasource creation or modification events with suspicious JDBC parameters
• Deploy web application firewall rules to inspect and block datasource configuration requests containing blocklist manipulation attempts

Monitoring Recommendations

• Enable detailed logging on the DataEase application for all datasource configuration changes
• Implement egress filtering to restrict outbound MySQL connections to known, trusted database servers only
• Set up alerts for file access anomalies that coincide with MySQL connection activity
• Regularly audit datasource configurations for unauthorized or suspicious entries

How to Mitigate CVE-2026-40899

Immediate Actions Required

• Upgrade DataEase to version 2.10.21 or later immediately
• Review existing datasource configurations for any unauthorized or suspicious entries
• Audit application logs for signs of exploitation attempts or unauthorized datasource modifications
• Implement network segmentation to prevent DataEase from initiating connections to untrusted MySQL servers

Patch Information

DataEase version 2.10.21 addresses this vulnerability by fixing the JDBC parameter blocklist bypass issue. The fix prevents the illegalParameters field from being overwritten during JSON deserialization. Organizations should update to version 2.10.21 or later as soon as possible. Refer to the GitHub Release v2.10.21 for download and upgrade instructions. Additional details are available in the GitHub Security Advisory GHSA-944x-93jf-h3rx.

Workarounds

• Implement network-level controls to restrict outbound MySQL connections from the DataEase server to a whitelist of approved database servers
• Deploy a web application firewall to inspect and reject datasource configuration requests that attempt to manipulate the illegalParameters field
• Restrict datasource creation and modification permissions to only trusted administrator accounts
• Consider running DataEase with reduced filesystem permissions to limit the impact of potential file read exploitation

# Network firewall rule to restrict outbound MySQL connections
# Allow only connections to trusted database server IP
iptables -A OUTPUT -p tcp --dport 3306 -d TRUSTED_DB_SERVER_IP -j ACCEPT
iptables -A OUTPUT -p tcp --dport 3306 -j DROP