Description

IBM Db2 11.5.0 through 11.5.9, and 12.1.0 through 12.1.5 for Linux, UNIX and Windows (includes DB2 Connect Server) could allow a remote authenticated attacker to cause a denial of service due to a null pointer dereference.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-14T20:16:41.173Z",
  "pubdate": "2026-09-14T20:16:41.173Z",
  "executiveSummary": "IBM Db2, including versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5, is susceptible to a denial-of-service vulnerability triggered by a null pointer dereference.\nThe vulnerability allows a remote, authenticated attacker to intentionally crash the database management system, leading to service disruption.\nThis flaw resides in the handling of internal database processes, where an improper state transition or memory reference leads to an application termination.\nSuccessful exploitation requires valid authentication to the Db2 instance, meaning the attacker must possess legitimate database credentials.\nThe primary risk is the loss of availability for the database server and all dependent applications, posing a significant operational threat.\nNo escalation of privileges is implied, but the resulting service outage effectively prevents legitimate users from accessing or modifying stored data until the service is restored by administrative intervention.",
  "technicalDetails": "The vulnerability is characterized as a null pointer dereference, a class of software defect where the application attempts to perform an operation on a memory pointer that has been initialized to zero or has become invalid due to an unhandled exception or race condition.\nIn the context of IBM Db2, this flaw occurs within the core database engine or associated server processes responsible for managing client requests.\nWhen a specific, malformed sequence of operations or an unexpected input is provided by an authenticated client, the database process fails to properly validate the object pointer before usage.\nUpon reaching the problematic instruction, the CPU attempts to dereference the null memory address, triggering a segmentation fault (SIGSEGV) or an equivalent hardware-level exception.\nBecause this error occurs within the core process, the operating system's signal handler terminates the process to prevent memory corruption or unpredictable state transitions, effectively forcing the database to go offline.\nThe attack flow begins with the authenticated user establishing a connection to the Db2 instance. The attacker must then issue specific SQL commands or administrative requests that traverse the vulnerable code path.\nAs the system processes these requests, an internal logic error results in a null memory pointer being assigned to a critical control structure. Subsequently, the application logic attempts to invoke a method or read data from this address.\nThe lack of prior sanitization or pointer null-checking logic at the point of consumption results in the immediate termination of the process thread or the entire DB2 instance.\nThis exploit is particularly dangerous because it does not require administrative privileges, merely a valid session, allowing any user with database access to disrupt business-critical operations remotely.\nThe vulnerability affects IBM Db2 (including DB2 Connect Server) on all supported Linux, UNIX, and Windows platforms within the identified version ranges. No complex heap spraying or code execution is required; the exploit is purely disruptive in nature, focusing on the instability of the service under targeted malformed input conditions."
}