CVE-2025-3050: IBM Db2 Denial of Service Vulnerability

CVE-2025-3050 Overview

IBM Db2 for Linux, UNIX and Windows (includes DB2 Connect Server) versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.1 contains a resource exhaustion vulnerability that could allow an authenticated user to cause a denial of service when using Q replication due to improper allocation of CPU resources. This vulnerability falls under CWE-770 (Allocation of Resources Without Limits or Throttling), indicating that the affected component fails to properly limit CPU resource consumption during Q replication operations.

Critical Impact

An authenticated attacker can trigger CPU resource exhaustion through Q replication functionality, leading to denial of service conditions that impact database availability and dependent enterprise applications.

Affected Products

• IBM Db2 for Linux 11.5.0 through 11.5.9
• IBM Db2 for Linux 12.1.0 through 12.1.1
• IBM Db2 for UNIX 11.5.0 through 11.5.9
• IBM Db2 for UNIX 12.1.0 through 12.1.1
• IBM Db2 for Windows 11.5.0 through 11.5.9
• IBM Db2 for Windows 12.1.0 through 12.1.1
• IBM DB2 Connect Server (all platforms, same version ranges)

Discovery Timeline

• 2025-05-29 - CVE-2025-3050 published to NVD
• 2025-06-09 - Last updated in NVD database

Technical Details for CVE-2025-3050

Vulnerability Analysis

This vulnerability represents a resource exhaustion condition in IBM Db2's Q replication feature. Q replication is a high-volume, low-latency replication solution that uses message queuing to capture and apply database changes. The vulnerability allows an authenticated user to trigger improper CPU resource allocation, which can consume excessive processor cycles and degrade or halt database operations.

The core issue stems from how the Q replication component handles certain operations without implementing proper resource throttling mechanisms. When exploited, the system fails to limit CPU consumption, allowing a malicious authenticated user to monopolize processing resources and cause service degradation for legitimate users.

The attack can be executed over the network and requires low privileges, making it accessible to any authenticated database user. While the vulnerability does not compromise data confidentiality or integrity, the availability impact is significant as it can render the database system unresponsive.

Root Cause

The root cause is classified under CWE-770: Allocation of Resources Without Limits or Throttling. The Q replication component in affected IBM Db2 versions fails to implement adequate controls on CPU resource allocation. This architectural oversight allows resource consumption to grow unchecked when specific replication operations are invoked, ultimately exhausting available CPU cycles and causing denial of service.

Attack Vector

The attack vector is network-based and requires authentication to the Db2 database system. An attacker with valid database credentials can exploit this vulnerability by initiating or manipulating Q replication operations in a manner that triggers the improper CPU resource allocation. The attack does not require user interaction and has low complexity, meaning exploitation is straightforward once authenticated access is obtained.

The vulnerability specifically affects the Q replication subsystem, which is commonly used in enterprise environments for real-time data replication across distributed database systems. Organizations relying on Q replication for high-availability or disaster recovery configurations are particularly at risk.

Detection Methods for CVE-2025-3050

Indicators of Compromise

• Abnormally high CPU utilization on systems running IBM Db2 Q replication services
• Unusual spikes in Q replication activity or related process execution
• Database performance degradation or unresponsive queries during replication operations
• System monitoring alerts indicating CPU exhaustion on Db2 server hosts

Detection Strategies

• Monitor CPU utilization patterns on Db2 database servers, particularly processes associated with Q replication (asnqcap, asnqapp, and related components)
• Implement database activity monitoring to detect anomalous Q replication operations from authenticated users
• Configure alerting thresholds for sustained high CPU usage on Db2 infrastructure
• Review database audit logs for unusual replication configuration changes or activity patterns

Monitoring Recommendations

• Deploy real-time CPU and resource monitoring on all systems hosting IBM Db2 with Q replication enabled
• Establish baseline metrics for normal Q replication CPU consumption to identify deviations
• Integrate Db2 monitoring with SIEM solutions to correlate resource exhaustion events with user activity
• Enable verbose logging for Q replication operations during security investigations

How to Mitigate CVE-2025-3050

Immediate Actions Required

• Review all authenticated users with access to Q replication functionality and restrict privileges where possible
• Implement resource limits and quotas at the operating system level for Db2 processes
• Monitor for any signs of exploitation while preparing to apply patches
• Consider temporarily disabling Q replication if not critical to operations until patching is complete

Patch Information

IBM has released security updates to address this vulnerability. Organizations should apply the appropriate patches as documented in the IBM Support Documentation. Affected versions include IBM Db2 11.5.0 through 11.5.9 and 12.1.0 through 12.1.1 across Linux, UNIX, and Windows platforms.

Consult the IBM security bulletin for specific fix pack versions and upgrade instructions applicable to your deployment. Ensure database backups are current before applying updates, and test patches in non-production environments where feasible.

Workarounds

• Restrict Q replication access to only essential, trusted administrative accounts
• Implement operating system-level CPU quotas using cgroups (Linux) or Job Objects (Windows) for Db2 processes
• Deploy network segmentation to limit database access to authorized application servers and administrators
• Enable enhanced monitoring and alerting for CPU resource consumption anomalies on Db2 hosts

# Example: Configure cgroups CPU limits for Db2 on Linux (RHEL/CentOS)
# Create cgroup for Db2 processes
sudo cgcreate -g cpu:/db2_limit

# Set CPU quota (e.g., limit to 80% of available CPU)
sudo cgset -r cpu.cfs_period_us=100000 /db2_limit
sudo cgset -r cpu.cfs_quota_us=80000 /db2_limit

# Move Db2 processes to the cgroup (replace PID with actual process IDs)
sudo cgclassify -g cpu:/db2_limit <DB2_PID>