CVE-2026-105466: IBM Db2 Denial of Service Vulnerability

CVE-2026-105466 Overview

CVE-2026-105466 affects IBM Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5. The vulnerability allows an authenticated attacker to trigger a denial of service when inserting data into a table that contains Extensible Markup Language (XML) columns under specific conditions. The flaw is categorized under [CWE-770]: Allocation of Resources Without Limits or Throttling. Exploitation requires low privileges and no user interaction, and it can be performed over the network.

Critical Impact
An authenticated attacker can exhaust database resources by inserting crafted data into XML columns, rendering IBM Db2 unavailable to legitimate users.

Affected Products

IBM Db2 11.5.0 through 11.5.9
IBM Db2 12.1.0 through 12.1.5
Deployments using tables with XML columns

Discovery Timeline

2026-10-12 - CVE-2026-105466 published to the National Vulnerability Database (NVD)
2026-10-13 - Last updated in NVD database

Technical Details for CVE-2026-105466

Vulnerability Analysis

The vulnerability resides in the IBM Db2 code path that handles INSERT operations against tables containing XML-typed columns. Under specific input conditions, the engine fails to constrain the resources it allocates while processing the XML payload. This absence of throttling allows the operation to consume excessive memory or processing capacity. The resulting resource pressure can halt query execution and make the database instance unresponsive.

The availability impact is high, while confidentiality and integrity remain unaffected. Exploitation requires an authenticated session with permission to insert into a table that uses XML columns. No user interaction is needed, and the attack can be delivered through standard database connectivity.

Root Cause

The root cause is improper resource allocation during XML column insertion, consistent with [CWE-770]. The Db2 engine does not enforce sufficient limits on resource usage when parsing or storing XML content under the triggering conditions. Repeated or crafted insert operations amplify the effect until the database service degrades or stops responding.

Attack Vector

An attacker with valid Db2 credentials and insert privileges on a target table submits INSERT statements that write XML content meeting the triggering conditions. Because the attack vector is network based, any client with reachability to the Db2 listener and valid authentication can initiate exploitation. The vulnerability does not require elevated database roles.

See the IBM Support Page for vendor technical details.

Detection Methods for CVE-2026-105466

Indicators of Compromise

Sudden spikes in memory or CPU usage on Db2 instances correlated with INSERT activity against XML columns
Repeated authenticated sessions issuing inserts into XML-typed columns from unusual client addresses
Db2 diagnostic log entries indicating resource exhaustion, aborted inserts, or instance unresponsiveness

Detection Strategies

Audit Db2 workloads for INSERT statements targeting tables that declare XML columns and baseline normal volume
Enable Db2 event monitors to capture statement execution metrics and flag sessions whose resource consumption deviates from baseline
Correlate database availability events with authentication logs to identify the originating account and client

Monitoring Recommendations

Alert on abnormal Db2 agent memory growth and connection stalls during insert workloads
Track failed or aborted transactions involving XML column operations in Db2 diagnostic logs
Forward Db2 audit and diagnostic data to a centralized analytics platform for continuous review

How to Mitigate CVE-2026-105466

Immediate Actions Required

Apply the fixed IBM Db2 release referenced in the IBM Support Page as soon as it is available in your environment
Restrict INSERT privileges on tables containing XML columns to accounts that require them
Rotate credentials for any Db2 accounts suspected of misuse and review their recent activity

Patch Information

IBM has published remediation guidance on the IBM Support Page for CVE-2026-105466. Administrators running IBM Db2 11.5.0 through 11.5.9 or 12.1.0 through 12.1.5 should review the advisory and upgrade to the version identified by IBM as containing the fix.

Workarounds

Limit database roles that can insert into tables with XML columns until the patch is applied
Enforce resource governance using Db2 Workload Manager to cap memory and CPU per connection or workload class
Place Db2 listeners behind network segmentation so only trusted application servers can reach them

bash

# Example: restrict INSERT privilege on an XML-bearing table
db2 "REVOKE INSERT ON TABLE schema.xml_table FROM PUBLIC"
db2 "GRANT INSERT ON TABLE schema.xml_table TO USER app_service"