CVE-2026-1121: Yonyou KSOA 9.0 SQL Injection Vulnerability

CVE-2026-1121 Overview

A SQL injection vulnerability has been discovered in Yonyou KSOA 9.0 affecting the /worksheet/del_workplan.jsp endpoint within the HTTP GET Parameter Handler component. The vulnerability allows remote attackers to manipulate the ID parameter to inject malicious SQL queries, potentially compromising database integrity, confidentiality, and availability. The exploit has been publicly disclosed, and the vendor was contacted but did not respond to the disclosure.

Critical Impact

Remote attackers can exploit this SQL injection vulnerability to read, modify, or delete database contents, potentially leading to unauthorized data access, data manipulation, or complete database compromise.

Affected Products

• Yonyou KSOA 9.0

Discovery Timeline

• 2026-01-18 - CVE-2026-1121 published to NVD
• 2026-01-18 - Last updated in NVD database

Technical Details for CVE-2026-1121

Vulnerability Analysis

This SQL injection vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component) exists in the Yonyou KSOA 9.0 enterprise application. The vulnerable endpoint /worksheet/del_workplan.jsp fails to properly sanitize user-supplied input in the ID parameter before incorporating it into SQL queries executed against the backend database.

The vulnerability is network-accessible with low attack complexity, requiring no authentication or user interaction. Successful exploitation can lead to unauthorized access to sensitive data stored in the database, modification or deletion of records, and potential further compromise of the underlying system depending on database permissions.

Root Cause

The root cause of this vulnerability is improper input validation and lack of parameterized queries in the del_workplan.jsp file. The application directly concatenates user-supplied input from the ID HTTP GET parameter into SQL statements without proper sanitization or escaping. This allows attackers to break out of the intended SQL query structure and execute arbitrary SQL commands.

Attack Vector

The attack is conducted remotely over the network by sending crafted HTTP GET requests to the vulnerable endpoint. An attacker can manipulate the ID parameter to inject SQL syntax that alters the query's logic. Typical attack patterns include:

The vulnerability can be exploited through standard SQL injection techniques targeting the ID parameter in GET requests to /worksheet/del_workplan.jsp. Attackers may use techniques such as UNION-based injection to extract data from other tables, boolean-based blind injection to enumerate database contents, or time-based blind injection when direct output is not available. Technical details and proof-of-concept information can be found in the GitHub Issue Report and VulDB advisory.

Detection Methods for CVE-2026-1121

Indicators of Compromise

• HTTP GET requests to /worksheet/del_workplan.jsp containing SQL syntax characters in the ID parameter (single quotes, double dashes, UNION, SELECT, etc.)
• Unusual database query patterns or errors in application logs
• Database audit logs showing unauthorized data access or extraction attempts
• Web application firewall alerts for SQL injection patterns targeting the KSOA application

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block SQL injection patterns in requests to /worksheet/del_workplan.jsp
• Enable detailed logging for the KSOA application and monitor for SQL error messages or anomalous query patterns
• Deploy database activity monitoring to detect unauthorized queries or bulk data extraction
• Use intrusion detection systems (IDS) with signatures for SQL injection attack patterns

Monitoring Recommendations

• Review web server access logs for requests containing URL-encoded SQL characters targeting the vulnerable endpoint
• Monitor database performance and query logs for unusual SELECT statements or error conditions
• Implement alerting for any access to the /worksheet/del_workplan.jsp endpoint if the application is not actively using this functionality
• Establish baseline database query patterns to identify anomalous activity

How to Mitigate CVE-2026-1121

Immediate Actions Required

• Restrict access to the /worksheet/del_workplan.jsp endpoint using network-level controls or web server configuration
• Implement input validation at the web application firewall level to block SQL injection attempts
• Consider disabling or removing the vulnerable endpoint if it is not critical to business operations
• Monitor for exploitation attempts using the detection strategies outlined above

Patch Information

As of the last update on 2026-01-18, no official patch has been released by Yonyou. The vendor was contacted during the disclosure process but did not respond. Organizations using Yonyou KSOA 9.0 should contact Yonyou support directly for patch availability or apply compensating controls. Additional technical information is available through VulDB.

Workarounds

• Deploy a web application firewall (WAF) with rules to filter SQL injection patterns in the ID parameter
• Implement network segmentation to limit access to the KSOA application from untrusted networks
• Use reverse proxy configuration to block or sanitize requests to the vulnerable endpoint
• Apply principle of least privilege to database accounts used by the KSOA application to minimize impact of successful exploitation

# Example: Apache mod_rewrite rule to block access to vulnerable endpoint
# Add to .htaccess or Apache configuration
RewriteEngine On
RewriteCond %{REQUEST_URI} ^/worksheet/del_workplan\.jsp [NC]
RewriteRule .* - [F,L]