Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to execute arbitrary code due to an integer underflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-20T22:17:10.483Z",
  "pubdate": "2026-08-20T22:17:10.483Z",
  "executiveSummary": "An integer underflow vulnerability has been identified in IBM AIX 7.2 and 7.3, as well as IBM PowerVM VIOS 4.1. This security flaw stems from improper handling of integer arithmetic within the affected software components, creating a memory corruption condition.\nSuccessful exploitation of this vulnerability allows a local, authenticated attacker to execute arbitrary code with elevated privileges on the target system. The primary impact of this vulnerability involves complete system compromise, unauthorized access to sensitive data, and potential disruption of critical virtualized workloads managed by PowerVM VIOS.\nThe risk implications are severe due to the potential for local privilege escalation and arbitrary code execution within the operating system kernel or privileged user-space components. Exploitation requires local access to the target system, meaning an attacker must already possess valid credentials or the ability to execute code locally.\nMitigation requires applying the appropriate vendor-supplied software fixes or interim fixes (ifixes) provided by IBM to remediate the underlying arithmetic calculation flaw.",
  "technicalDetails": "The vulnerability is rooted in an integer underflow condition occurring within specific system components of IBM AIX 7.2, AIX 7.3, and IBM PowerVM VIOS 4.1. An integer underflow arises when an arithmetic operation results in a value that is less than the minimum representable value for the allocated integer data type, typically wrapping around to a large positive number when handled as an unsigned integer.\nIn the context of this vulnerability, the flawed arithmetic calculation is typically utilized to determine memory allocation sizes, buffer offsets, or loop boundaries within a vulnerable binary or kernel extension. When the underflow occurs, subsequent memory management operations allocate a buffer significantly smaller than anticipated or process data using incorrect bounds.\nAn attacker leverages this behavior by supplying specially crafted inputs or parameters—often via system calls, ioctl interfaces, or local inter-process communication mechanisms—that trigger the improper arithmetic calculation. Because the allocated buffer size does not match the size of the data being written or processed, a subsequent heap-based or stack-based memory corruption (such as a buffer overflow or out-of-bounds write) occurs.\nThe attack flow proceeds as follows: First, the local attacker establishes execution context on the target IBM AIX or PowerVM VIOS instance. Second, the attacker interacts with the vulnerable component, passing meticulously engineered arguments designed to force the target application or kernel routine into an integer underflow state. Third, the resulting miscalculation causes a memory corruption event during data copying or buffering operations. Finally, by carefully controlling the layout of adjacent memory structures, the attacker overwrites critical function pointers, control data, or execution context, enabling the execution of arbitrary machine code.\nThe affected components reside within the core operating system architecture of IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1. Exploitation requires local access to the system, but does not inherently mandate network exposure. Depending on the exact vulnerable interface, execution may occur within user space or kernel space, directly dictating whether the resulting arbitrary code execution yields local user privileges or full administrative (root/hypervisor) control."
}