CVE-2026-104332: 
IBM Db2 vulnerability analysis and mitigation

CVE-2026-104332 is a denial-of-service vulnerability in IBM Db2 caused by a stack-based buffer overflow (CWE-121) triggered when executing a specially crafted query involving a Materialized Query Table. It affects IBM Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5. The vulnerability was published on October 12, 2026, with a patch made available the same day. It carries a CVSS v3.1 base score of 5.5 (Medium) (GitHub Advisory, IBM Support).

The vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), occurring within IBM Db2's query processing engine when handling Materialized Query Table (MQT) operations. An attacker with local database access can craft a malicious SQL query targeting MQT functionality to trigger a stack buffer overflow, causing the Db2 service to crash or hang. The attack vector is local, requires low privileges (authenticated database user), and no user interaction, making it exploitable by any authenticated database user without elevated permissions (GitHub Advisory, IBM Support).

Successful exploitation results in a denial-of-service condition, crashing or hanging the IBM Db2 database service and rendering it unavailable to all users and dependent applications. The impact is limited to availability — there is no confidentiality or integrity impact, meaning data is not exposed or modified. The scope is unchanged, confining the impact to the Db2 instance itself without enabling lateral movement or privilege escalation (GitHub Advisory).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable, reflecting the requirement for local, authenticated access. The EPSS score is 0.0, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (GitHub Advisory, IBM Support).

IBM has released patches addressing this vulnerability; users should upgrade IBM Db2 to a version beyond 11.5.9 (for the 11.5.x line) or beyond 12.1.5 (for the 12.1.x line). As interim mitigations, administrators should restrict SQL query execution privileges to trusted users only and monitor for unusual or complex queries involving Materialized Query Tables. Implementing query validation controls and auditing database access logs can further reduce risk (IBM Support, GitHub Advisory).