CVE-2026-10109: IBM Db2 RCE Vulnerability

CVE-2026-10109 Overview

IBM Db2 contains a remote code execution vulnerability in its pre-authentication Distributed Relational Database Architecture (DRDA) handshake handling. The flaw affects IBM Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.4. Attackers can exploit this vulnerability over the network without authentication or user interaction. Successful exploitation allows arbitrary code execution in the context of the Db2 database service. The vulnerability is classified under CWE-94: Improper Control of Generation of Code.

Critical Impact
Unauthenticated remote attackers can execute arbitrary code on IBM Db2 servers by sending crafted DRDA handshake packets before authentication occurs.

Affected Products

IBM Db2 versions 11.5.0 through 11.5.9
IBM Db2 versions 12.1.0 through 12.1.4
Db2 database server instances exposing the DRDA listener

Discovery Timeline

2026-06-30 - CVE-2026-10109 published to the National Vulnerability Database
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-10109

Vulnerability Analysis

The vulnerability resides in the DRDA protocol handler used by IBM Db2 for client-server communication. DRDA governs how clients negotiate sessions, exchange metadata, and submit SQL requests. The handshake phase runs before authentication completes, exposing parsing logic to unauthenticated peers.

Improper handling of handshake data allows an attacker to influence code generation or execution paths within the Db2 server process. Because the flaw is reachable pre-authentication, attackers only need network access to the DRDA listener, typically TCP port 50000. The Db2 service commonly runs with elevated privileges, so successful exploitation can compromise the underlying host and stored data.

Root Cause

The root cause is improper validation during construction or interpretation of handshake structures, mapped to CWE-94: Improper Control of Generation of Code. Attacker-controlled fields in the initial DRDA exchange are processed without adequate boundary and type checks, permitting injection into execution logic.

Attack Vector

Exploitation requires network reachability to a Db2 DRDA endpoint. An attacker sends a crafted DRDA connection request that manipulates handshake fields to trigger code execution before credentials are validated. Refer to the IBM Support Page for vendor-supplied technical details.

// No verified public proof-of-concept code is available.
// Refer to the IBM Support advisory for technical guidance.

Detection Methods for CVE-2026-10109

Indicators of Compromise

Unexpected child processes spawned by the db2sysc or Db2 instance owner account
Outbound network connections initiated by Db2 processes to unfamiliar IP addresses
New or modified files in Db2 instance directories without corresponding administrative activity
Anomalous crashes or restarts of the Db2 service coinciding with inbound DRDA traffic

Detection Strategies

Inspect DRDA traffic on TCP port 50000 for malformed handshake structures and oversized fields
Monitor Db2 diagnostic logs (db2diag.log) for parsing errors during connection initialization
Correlate pre-authentication connection failures with subsequent process anomalies on the database host
Deploy network intrusion detection signatures targeting anomalous DRDA EXCSAT and ACCSEC flows

Monitoring Recommendations

Enable audit logging for all DRDA connection attempts, including failed handshakes
Alert on process creation events where the parent is a Db2 service binary
Track file integrity of Db2 installation directories and shared libraries
Baseline outbound network traffic from database hosts to identify deviations

How to Mitigate CVE-2026-10109

Immediate Actions Required

Apply the IBM-supplied patch or upgrade to a fixed Db2 release as documented in the IBM Support Page
Restrict network access to the DRDA listener using firewalls or host-based access control lists
Inventory all Db2 instances, including development and test systems, to identify vulnerable versions
Review database audit logs for suspicious pre-authentication connection activity

Patch Information

IBM has published remediation guidance on the IBM Support Page. Administrators should upgrade Db2 11.5.x and 12.1.x deployments to the fixed release levels identified in the advisory. Apply the update to all instances, including standby, HADR, and pureScale members.

Workarounds

Limit exposure of the DRDA listener to trusted management networks only
Place Db2 servers behind network segmentation with strict ingress filtering on port 50000
Disable remote connectivity on instances that only require local access until patching is complete
Enforce TLS-terminating proxies or database firewalls capable of validating DRDA handshake structure

bash

# Example: restrict DRDA port access with iptables
iptables -A INPUT -p tcp --dport 50000 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 50000 -j DROP