CVE-2026-18166: IBM Db2 Information Disclosure Vulnerability

CVE-2026-18166 Overview

CVE-2026-18166 is an improper authorization vulnerability [CWE-284] affecting IBM Db2 for Linux, UNIX, and Windows (LUW), including DB2 Connect Server. The flaw resides in the handling of the CREATE WRAPPER command and allows a remote authenticated attacker to obtain sensitive information. Affected releases include Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5. IBM published advisory details on the IBM Support site.

Critical Impact
An authenticated database user can bypass authorization controls on CREATE WRAPPER to read sensitive data they should not access, with a scope change extending impact beyond the vulnerable component.

Affected Products

IBM Db2 for Linux, UNIX and Windows 11.5.0 through 11.5.9
IBM Db2 for Linux, UNIX and Windows 12.1.0 through 12.1.5
IBM DB2 Connect Server (bundled with affected Db2 LUW releases)

Discovery Timeline

2026-10-12 - CVE-2026-18166 published to the National Vulnerability Database (NVD)
2026-10-13 - Last updated in NVD database

Technical Details for CVE-2026-18166

Vulnerability Analysis

The vulnerability stems from an authorization defect in the Db2 federation subsystem. The CREATE WRAPPER statement registers a wrapper module that enables Db2 to communicate with external data sources through its federation feature. Db2 does not correctly validate the invoking user's privileges before processing the wrapper creation request.

An authenticated database user with low privileges can leverage this gap to interact with wrapper functionality reserved for higher-privileged roles. The resulting exposure provides read access to sensitive information handled by federated components. The scope change in the vulnerability metric indicates the impact crosses the authorization boundary of the original security context.

Root Cause

The root cause maps to [CWE-284] Improper Access Control. Db2 fails to enforce the required authorization checks on the CREATE WRAPPER DDL path. Any session holding a valid Db2 login can reach the vulnerable code without the privileges normally required to register a federation wrapper.

Attack Vector

Exploitation requires network access to the Db2 instance and valid database credentials. No user interaction is needed. After authenticating, the attacker issues a crafted CREATE WRAPPER statement to trigger disclosure of sensitive information. Confidentiality is impacted; integrity and availability are not. Refer to the IBM Support Documentation for vendor-provided technical specifics.

Detection Methods for CVE-2026-18166

Indicators of Compromise

Unexpected CREATE WRAPPER statements in Db2 audit logs issued by accounts without federation administration privileges.
Creation of federation wrapper objects outside documented change windows or by non-DBA accounts.
Anomalous queries referencing newly created wrappers shortly after their creation.

Detection Strategies

Enable Db2 audit facility (db2audit) with the EXECUTE and OBJMAINT categories to capture DDL activity, including CREATE WRAPPER.
Correlate authentication events with DDL execution to flag low-privilege sessions performing federation-related changes.
Baseline normal federation administration activity and alert on deviations.

Monitoring Recommendations

Forward Db2 audit output to a centralized logging platform for retention and correlation.
Review SYSCAT.WRAPPERS catalog changes on a scheduled cadence and alert on new entries.
Monitor failed and successful logins from unexpected network segments to limit the authenticated attack surface.

How to Mitigate CVE-2026-18166

Immediate Actions Required

Apply the IBM-provided fix referenced in the IBM Support Documentation for the affected 11.5.x and 12.1.x release trains.
Audit Db2 accounts and revoke unnecessary privileges, enforcing least privilege for federation operations.
Review existing federation wrappers for unauthorized or unknown entries and remove them where appropriate.

Patch Information

IBM has released remediation guidance for Db2 LUW versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5. Consult the IBM Support Documentation for the fix pack level and interim fix details applicable to each supported release. DB2 Connect Server deployments should be updated in alignment with the underlying Db2 LUW build.

Workarounds

Restrict network access to Db2 listeners so only trusted application tiers and administrators can authenticate.
Limit account creation and enforce strong password or certificate-based authentication to reduce the pool of users capable of reaching the vulnerable code path.
Monitor and restrict use of federation features where business requirements do not depend on them.

bash

# Example: enable Db2 audit for DDL events (OBJMAINT) and review wrapper catalog
db2audit configure scope objmaint status both errortype normal
db2audit start
db2 "SELECT WRAPNAME, WRAPTYPE, CREATE_TIME FROM SYSCAT.WRAPPERS ORDER BY CREATE_TIME DESC"