CVE-2025-2518: IBM Db2 Denial of Service Vulnerability

CVE-2025-2518 Overview

IBM Db2 for Linux, UNIX and Windows (includes DB2 Connect Server) is vulnerable to a denial of service condition where the database server may crash when processing a specially crafted query. This vulnerability affects versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.1, potentially disrupting critical database operations and business continuity for organizations relying on IBM Db2 as their enterprise database solution.

Critical Impact
Unauthenticated remote attackers can crash IBM Db2 database servers by sending specially crafted queries, causing service disruption and potential data unavailability for dependent applications.

Affected Products

IBM Db2 for Linux versions 11.5.0 through 11.5.9
IBM Db2 for UNIX versions 11.5.0 through 11.5.9
IBM Db2 for Windows versions 11.5.0 through 11.5.9
IBM Db2 for Linux versions 12.1.0 through 12.1.1
IBM Db2 for UNIX versions 12.1.0 through 12.1.1
IBM Db2 for Windows versions 12.1.0 through 12.1.1
IBM DB2 Connect Server (all affected platforms)

Discovery Timeline

2025-05-29 - CVE-2025-2518 published to NVD
2025-06-09 - Last updated in NVD database

Technical Details for CVE-2025-2518

Vulnerability Analysis

This vulnerability is classified under CWE-789 (Memory Allocation with Excessive Size Value), indicating that the IBM Db2 database engine improperly handles memory allocation when processing certain query structures. When an attacker submits a specially crafted query, the database server fails to properly validate or limit memory allocation requests, leading to conditions that cause the server process to crash.

The attack can be executed remotely over the network without requiring authentication or user interaction. This makes the vulnerability particularly dangerous in environments where Db2 instances are exposed to untrusted networks or where database access is not strictly controlled. A successful exploitation results in complete service unavailability until the database is manually restarted.

Root Cause

The root cause of this vulnerability lies in improper memory management within the query processing engine. Specifically, the database fails to implement adequate bounds checking or resource limits when handling query parameters that influence memory allocation. When a malformed query triggers an excessive memory allocation request, the system cannot gracefully handle the resulting condition, leading to a crash of the Db2 server process.

Attack Vector

The vulnerability can be exploited through network-based attacks targeting the database service. An attacker with network access to the Db2 listener port can submit a specially crafted SQL query designed to trigger the memory allocation flaw. The attack does not require:

Valid database credentials
Prior knowledge of database schema
User interaction on the target system

The specially crafted query exploits weaknesses in the query parser or execution engine, causing the server to attempt an allocation of memory that exceeds safe operational parameters. This results in immediate termination of the database server process, denying service to all connected clients and applications.

Detection Methods for CVE-2025-2518

Indicators of Compromise

Unexpected Db2 server process terminations without clear operational cause
Repeated crash events correlated with specific client connection timestamps
Database diagnostic logs showing memory allocation failures or abnormal query patterns
System event logs indicating Db2 service restarts or failures

Detection Strategies

Monitor Db2 diagnostic logs (db2diag.log) for crash events and memory-related errors
Implement network traffic analysis to identify anomalous query patterns targeting Db2 ports
Configure alerting on database service availability and unexpected restarts
Deploy intrusion detection signatures for known DoS attack patterns against database services

Monitoring Recommendations

Enable comprehensive logging of database connections and query submissions
Implement real-time monitoring of Db2 service health and availability metrics
Configure automated alerts for database crashes or unexpected restarts
Monitor network connections to Db2 listener ports for suspicious activity patterns

How to Mitigate CVE-2025-2518

Immediate Actions Required

Review the IBM Security Advisory for specific patch information
Inventory all IBM Db2 installations to identify affected versions (11.5.0-11.5.9, 12.1.0-12.1.1)
Restrict network access to Db2 listener ports using firewall rules
Implement network segmentation to limit exposure of database servers to untrusted networks
Ensure database backup procedures are current and tested for rapid recovery

Patch Information

IBM has released security updates to address this vulnerability. Administrators should consult the IBM Support Page for detailed patch information and upgrade instructions. Apply the latest security updates for IBM Db2 as soon as possible to remediate this vulnerability.

Workarounds

Implement strict firewall rules to limit database access to trusted hosts only
Deploy a Web Application Firewall (WAF) or database firewall to filter malicious queries
Use connection pooling with query validation to sanitize incoming requests
Monitor and rate-limit database connections from individual sources
Consider implementing database proxy solutions that can inspect and filter SQL traffic

bash

# Example: Restrict Db2 port access using iptables (Linux)
# Allow only trusted application servers to connect to Db2
iptables -A INPUT -p tcp --dport 50000 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 50000 -j DROP

# Verify Db2 version to check if affected
db2level