Description

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

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-20T22:17:07.817Z",
  "pubdate": "2026-08-20T22:17:07.817Z",
  "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. The primary impact of successful exploitation is the acquisition of elevated privileges on the target system, potentially allowing a local malicious actor to bypass security controls and execute arbitrary code with higher privilege levels.\nThe affected products include IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM VIOS version 4.1. The risk implications are severe for multi-tenant or shared environments, as a compromised low-privileged account can escalate to administrative capabilities.\nAttacker capabilities require local access to the system with pre-existing execution privileges. The exploitation process relies on the attacker's ability to manipulate file system states or shared resources asynchronously during the execution window between the security validation check and the subsequent resource utilization operation.",
  "technicalDetails": "The root cause of the vulnerability stems from an insecure synchronization mechanism or design flaw involving asynchronous state validation, specifically a time-of-check to time-of-use (TOCTOU) race condition within the affected operating system components.\nVulnerable components involve internal routines handling resource access, permission validation, or file system operations within IBM AIX 7.2, AIX 7.3, and IBM PowerVM VIOS 4.1.\nAuthentication requirements dictate that the attacker must already possess local access to the target system. Privilege requirements are minimal prior to exploitation, as standard local user privileges are sufficient to initiate the race condition. Network exposure is absent, as the attack vector is strictly local and cannot be exploited remotely.\nThe attack flow proceeds as follows: First, the vulnerable component performs a security check on a target resource, verifying permissions or properties at the time of check (TOC). Second, an exploitable time window exists between this validation and the actual utilization of the resource. Third, during this asynchronous window, a locally authenticated attacker rapidly manipulates the targeted resource, swapping it with a malicious substitute or altering its attributes. Fourth, the system utilizes the resource at the time of use (TOU) based on the outdated validation results, bypassing intended security controls.\nPost-exploitation impact includes unauthorized privilege escalation, allowing the local attacker to achieve elevated execution rights, potentially compromising the integrity, confidentiality, and availability of the underlying operating system or virtualized environment."
}