CVE-2023-27555 in DB2
Summary
by MITRE • 04/28/2023
IBM Db2 for Linux, UNIX and Windows (includes DB2 Connect Server) 11.5 is vulnerable to a denial of service when attempting to use ACR client affinity for unfenced DRDA federation wrappers. IBM X-Force ID: 249187.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/24/2023
The vulnerability identified as CVE-2023-27555 affects IBM Db2 for Linux, UNIX and Windows versions including DB2 Connect Server 11.5, representing a significant denial of service weakness that impacts database federation capabilities. This vulnerability specifically manifests when attempting to utilize ACR client affinity functionality within unfenced DRDA federation wrappers, creating a potential disruption vector for database operations. The flaw exists within the database management system's handling of client affinity mechanisms during distributed database requests, where the system fails to properly manage resource allocation and connection states when federation wrappers are employed without proper fencing controls.
The technical implementation of this vulnerability stems from insufficient validation and error handling within the DRDA (Distributed Relational Database Architecture) protocol processing layer of IBM Db2. When ACR client affinity is enabled for federation wrappers that lack proper fencing mechanisms, the system encounters a condition where resource exhaustion or improper state transitions occur during connection establishment or request processing. This results in the database server becoming unresponsive or terminating connections unexpectedly, effectively rendering the affected database services unavailable to legitimate users and applications. The vulnerability operates at the protocol level where DRDA requests are processed through federation wrappers, making it particularly dangerous as it can impact database availability for critical business applications that rely on distributed database operations.
From an operational impact perspective, this vulnerability creates substantial risk for organizations utilizing IBM Db2 in distributed database environments where federation and client affinity features are employed. The denial of service condition can lead to complete unavailability of database services, requiring manual intervention to restore system functionality through restart procedures or manual resource cleanup. This vulnerability directly impacts business continuity and can result in significant downtime costs, particularly in environments where database availability is critical for enterprise applications, transaction processing, and data integration services. The vulnerability affects both the database server and client applications that depend on proper federation functionality, potentially causing cascading failures throughout interconnected systems that rely on distributed database operations.
Organizations should implement immediate mitigations including disabling ACR client affinity for federation wrappers when unfenced configurations are in use, applying the latest IBM security patches and updates, and implementing monitoring solutions to detect abnormal connection patterns or resource exhaustion conditions. The vulnerability aligns with CWE-400 weakness category related to resource exhaustion and may be categorized under ATT&CK technique T1499 for endpoint denial of service. Network segmentation and access controls should be implemented to limit exposure, while system administrators should establish alerting mechanisms for unusual database connection behavior. Additionally, organizations should conduct thorough testing of database configurations to identify all instances where federation wrappers are used without proper fencing controls, as these represent the primary attack surface for this vulnerability. The mitigation strategy should also include implementing connection pooling and resource management controls to prevent exploitation of the resource exhaustion conditions that lead to the denial of service state.