CVE-2026-86093 in Db2
Summary
by MITRE • 09/10/2026
IBM Db2 11.5.0 through 11.5.9, and 12.1.0 through 12.1.5 could allow an attacker with the ability to control or impersonate a DRDA server endpoint to execute arbitrary commands on Db2 clients due to a stack-based buffer overflow that improperly copies user-controlled data into a fixed-size stack buffer without bounds checking.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified in IBM Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5 represents a critical security flaw rooted in improper input validation within the Distributed Relational Database Architecture server endpoint handling logic. This specific issue is classified as CWE-121, which denotes a stack-based buffer overflow condition where data copied into a fixed-size memory location on the call stack exceeds its allocated boundaries due to missing bounds checking mechanisms. The root cause lies in the application's failure to verify that incoming user-controlled data fits within the predefined limits of the destination buffer before performing the copy operation. This lack of validation allows an attacker who can control or impersonate a DRDA server endpoint to inject malicious payloads directly into the execution flow by overflowing adjacent memory regions on the stack, potentially overwriting return addresses or function pointers with shellcode designed for arbitrary command execution.
From an operational perspective, this vulnerability poses a severe risk because it enables remote code execution without requiring authentication if the attacker can successfully position themselves as a trusted DRDA server endpoint in the network path between clients and databases. The exploitation of this flaw allows adversaries to gain full control over the affected Db2 client systems, leading to complete compromise of confidentiality, integrity, and availability of data processed by these clients. Such an attack vector aligns with ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques like PowerShell or Windows Command Shell, as well as potential lateral movement strategies if the compromised client serves as a pivot point within the enterprise network. The impact extends beyond individual system compromise to include potential data exfiltration, installation of persistent backdoors, and disruption of critical database services that rely on these clients for connectivity.
Mitigation efforts must prioritize immediate patching by upgrading IBM Db2 installations to versions 11.5.10 or later, which contain the necessary code fixes to enforce strict bounds checking during buffer operations. In environments where immediate patching is not feasible due to operational constraints, network segmentation strategies should be implemented to restrict DRDA traffic between clients and servers to trusted subnets only. Additionally, deploying intrusion detection systems configured with signatures for known exploitation patterns of stack-based overflows can provide an additional layer of defense by identifying anomalous packet sizes or malformed protocol sequences indicative of this vulnerability being actively exploited. Security teams should also enforce strict authentication policies for DRDA connections and monitor logs for unusual connection attempts from untrusted endpoints to detect potential reconnaissance or initial access phases associated with this threat vector.