CVE-2025-36407 Overview
CVE-2025-36407 is a denial of service vulnerability in IBM Db2 that an authenticated local attacker can trigger using a specially crafted query containing ALTER TABLE operations. The flaw is classified under [CWE-1284: Improper Validation of Specified Quantity in Input] and affects IBM Db2 deployments on Linux, UNIX, and Windows platforms. Successful exploitation causes the Db2 database engine to become unavailable, disrupting applications and services that rely on it. The vulnerability requires low privileges and no user interaction, but exploitation is constrained to a local attack vector.
Critical Impact
An authenticated user can crash or hang the Db2 database server through a malformed ALTER TABLE query, resulting in service unavailability for all dependent applications.
Affected Products
- IBM Db2 on Linux
- IBM Db2 on UNIX
- IBM Db2 on Windows
Discovery Timeline
- 2026-01-30 - CVE-2025-36407 published to NVD
- 2026-02-09 - Last updated in NVD database
Technical Details for CVE-2025-36407
Vulnerability Analysis
The vulnerability resides in how IBM Db2 processes ALTER TABLE Data Definition Language (DDL) statements. When a crafted query supplies input that the Db2 engine does not properly validate, the database server enters an error state that terminates or hangs the affected process. Because Db2 services many concurrent sessions from a single instance, a single malicious statement disrupts availability for all connected applications. The CWE-1284 classification indicates that the engine fails to validate a specified quantity within the input, allowing an attacker to drive the parser or executor into an unsafe state.
Root Cause
The defect stems from improper validation of input parameters within the ALTER TABLE execution path. Db2 does not adequately constrain values that influence resource allocation or operation bounds before processing the DDL statement. As a result, attacker-controlled input reaches code paths that assume well-formed quantities, producing the denial of service condition.
Attack Vector
An attacker requires an authenticated Db2 session and the privileges needed to issue ALTER TABLE statements against a target object. The attack is local to the database instance and does not require user interaction. The attacker sends the crafted DDL statement through any supported Db2 client interface, after which the engine fails and becomes unresponsive. Confidentiality and integrity are not affected, but availability impact is high.
No public proof-of-concept code is available for this vulnerability. Refer to the IBM security advisory for vendor-supplied technical details.
Detection Methods for CVE-2025-36407
Indicators of Compromise
- Unexpected Db2 instance crashes, restarts, or hangs immediately following execution of ALTER TABLE statements.
- Db2 diagnostic logs (db2diag.log) containing fatal errors or trap entries correlated with DDL processing.
- Abnormal session terminations recorded in Db2 audit logs after authenticated DDL activity.
Detection Strategies
- Enable Db2 audit facility (db2audit) to capture all ALTER TABLE events with the issuing authorization ID and timestamp.
- Correlate Db2 service interruptions with preceding DDL activity from non-administrative accounts.
- Baseline normal DDL behavior per application account, then alert on ALTER TABLE statements issued by accounts that do not typically perform schema changes.
Monitoring Recommendations
- Forward db2diag.log and audit records to a centralized log analytics or SIEM platform for retention and alerting.
- Monitor Db2 instance process health and connection counts for sudden drops indicative of an engine failure.
- Track authentication events that grant DDL-capable privileges, especially ALTERIN and table owner grants.
How to Mitigate CVE-2025-36407
Immediate Actions Required
- Apply the IBM Db2 fix referenced in the IBM Support advisory as soon as it is available for your version.
- Inventory all Db2 instances on Linux, UNIX, and Windows and verify their patch status against the vendor advisory.
- Restrict ALTER TABLE privileges to administrative roles and revoke unnecessary DDL grants from application accounts.
Patch Information
IBM has published remediation guidance on the IBM Support page for CVE-2025-36407. Administrators should consult the advisory to identify the fix pack or special build that applies to their installed Db2 version and platform, then schedule installation following standard change management procedures.
Workarounds
- Limit local and authenticated access to Db2 instances to trusted administrators where feasible.
- Revoke ALTER privileges from accounts that do not require schema modification capability.
- Implement application-tier separation so that compromised low-privilege accounts cannot issue DDL against production schemas.
- Enable database activity monitoring to alert on unexpected ALTER TABLE execution patterns.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.