Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to gain root privileges due to a time-of-check to time-of-use (TOCTOU) race condition.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.3",
  "pubDate": "2026-08-20T15:17:29.130Z",
  "pubdate": "2026-08-20T15:17:29.130Z",
  "executiveSummary": "This vulnerability is classified as a time-of-check to time-of-use (TOCTOU) race condition flaw affecting IBM AIX and IBM PowerVM VIOS operating environments.\nThe primary impact of this security defect is local privilege escalation, which allows an authenticated local attacker to elevate their execution context and successfully gain root privileges on the targeted system.\nThe affected products include IBM AIX versions 7.2 and 7.3, alongside IBM PowerVM VIOS version 4.1.\nThe risk implications are severe, as successful exploitation circumvents standard operating system access controls, granting complete administrative control to unauthorized users and compromising overall system confidentiality, integrity, and availability.\nThe attacker capabilities required to exploit this vulnerability include local system access with authenticated user privileges.\nThe exploitation requirements rely on successfully winning a race condition window by manipulating shared system resources or file states between the validation check phase and the actual usage phase within the vulnerable execution logic.",
  "technicalDetails": "The root cause of the vulnerability stems from a time-of-check to time-of-use (TOCTOU) race condition inherent in the privilege management or resource handling routines within IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1.\nA TOCTOU race condition occurs when a software application checks the state of a resource (such as a file, symbolic link, or directory) before performing an operation on that resource, but the state of the resource changes between the check and the use operations.\nThe vulnerable component involves internal system binaries or kernel mechanisms responsible for handling privileged operations or file system interactions where temporary states are validated prior to execution.\nThe authentication and privilege requirements dictate that the threat actor must already possess local access to the target system with standard user credentials to initiate the attack sequence.\nThe network exposure for this vulnerability is entirely local, meaning remote network vector exploitation is not directly applicable unless chained with a separate remote access vector.\nThe step-by-step attack flow begins with the local attacker identifying a targeted privileged operation or utility that suffers from the race condition vulnerability. The attacker prepares a controlled environment designed to rapidly manipulate the target resource state. During execution, the application performs a security check on a benign state of the resource. Immediately following this time-of-check, the attacker rapidly swaps or alters the resource to a malicious state before the application performs the time-of-use action. Because the validation check is bypassed or invalidated by the rapid state change, the application executes the privileged routine against the attacker-controlled resource.\nThe post-exploitation impact of this vulnerability results in full administrative takeover, enabling the attacker to execute arbitrary system commands with root privileges, install persistent backdoors, modify system security policies, and access sensitive data across the compromised IBM AIX or IBM PowerVM VIOS instance."
}