CVE-2026-86573 in Disk Array Driver for AIX
Summary
by MITRE • 10/14/2026
Out-of-bounds write vulnerability in Hitachi Disk Array Driver for AIX and Hitachi Disk Array Driver for Virtual I/O Server.
This issue affects Hitachi Disk Array Driver for AIX: from 01-00 before 01-23-/A; Hitachi Disk Array Driver for Virtual I/O Server: from 01-04 before 01-23-/A.
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Analysis
by VulDB Data Team • 10/14/2026
The identified vulnerability represents a critical out-of-bounds write condition within the Hitachi Disk Array Driver software, specifically impacting versions of the driver designed for AIX and Virtual I/O Server environments. This flaw is present in releases ranging from version 01-00 up to but not including version 01-23-/A for both operating system platforms. An out-of-bounds write occurs when a program writes data to a memory location outside the boundaries of the intended buffer or array structure. In the context of kernel-mode drivers, such as those managing hardware storage arrays, this type of error is particularly severe because it allows an attacker with local access to manipulate critical system memory structures that are typically protected from user-space interference.
From a technical perspective, the vulnerability likely stems from insufficient validation checks on input parameters or index values before they are used to calculate memory addresses for write operations. When the driver processes commands related to disk array management, it may fail to verify whether the calculated destination address falls within the allocated kernel heap or stack space. If an attacker can trigger this code path with crafted inputs that result in a pointer arithmetic error exceeding the buffer limits, they gain the ability to overwrite adjacent memory regions. This could include overwriting function pointers, return addresses on the call stack, or other critical data structures such as object headers or security tokens within the kernel space.
The operational impact of this vulnerability is significant due to its potential for privilege escalation and system compromise. Since the affected components operate at ring 0 level with full access to hardware resources, successful exploitation can lead to arbitrary code execution in kernel mode. This effectively grants an attacker complete control over the underlying host operating system, allowing them to bypass all standard security controls including Access Control Lists (ACLs), mandatory access policies, and audit mechanisms. Furthermore, because these drivers are integral to storage connectivity, compromising them could also facilitate denial of service conditions by corrupting critical kernel data structures, leading to immediate system crashes or instability that disrupts availability for connected virtual machines or physical hosts relying on the Hitachi storage infrastructure.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-787: Out-of-bounds Write, which describes writing data outside of the intended buffer boundary. In terms of attack vectors and tactics, this flaw supports techniques categorized under MITRE ATT&CK T1055: Process Injection or more specifically kernel-level process injection variants where attackers modify memory to execute malicious code within a trusted system process. It also relates to CWE-120: Buffer Copy without Checking Size of Input when the root cause involves improper bounds checking during data transfer operations initiated by driver routines handling storage commands.
Mitigation strategies must prioritize immediate software updates as provided by the vendor. Organizations running affected versions of the Hitachi Disk Array Driver for AIX or Virtual I/O Server should upgrade to version 01-23-/A or later, where the out-of-bounds write condition has been remediated through improved input validation and boundary checks within the driver codebase. In environments where immediate patching is not feasible due to operational constraints, network segmentation strategies can help limit lateral movement by isolating systems running vulnerable drivers from untrusted networks. Additionally, deploying host-based intrusion detection systems that monitor for anomalous kernel memory access patterns or unexpected privilege escalation events may provide early warning indicators of exploitation attempts. Regular auditing of driver versions and adherence to strict change management protocols are essential components of a defense-in-depth strategy against such low-level system vulnerabilities.