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 a time-of-check to time-of-use (TOCTOU) race condition.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.0",
  "pubDate": "2026-08-20T15:17:28.263Z",
  "pubdate": "2026-08-20T15:17:28.263Z",
  "executiveSummary": "This vulnerability is classified as a time-of-check to time-of-use (TOCTOU) race condition affecting IBM AIX and IBM PowerVM VIOS. The flaw allows a local attacker to execute arbitrary code with elevated privileges under specific execution conditions. The affected products include IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1. The risk implication involves potential system compromise, unauthorized privilege escalation, and execution of malicious code within the operating system kernel or privileged administrative contexts. Successful exploitation requires local access to the target host and the ability to manipulate file system states or execution routines during the race condition window. The attack does not inherently require network exposure, relying instead on local system interaction to trigger the asynchronous state discrepancy between the initial security validation and the subsequent execution phase.",
  "technicalDetails": "The root cause of the vulnerability stems from an insecure synchronization mechanism involving file system operations or resource validation, specifically a time-of-check to time-of-use (TOCTOU) race condition. In vulnerable components of IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1, the operating system performs a security check on a resource—such as verifying file permissions, ownership, or path validity—prior to executing an operation on that same resource. Because there is a temporal gap between the time the check is performed and the time the resource is actually used, a local attacker can manipulate the targeted resource during this critical window.\nThe exploitation method relies on asynchronous race condition manipulation. The attacker initiates a privileged or sensitive operation that triggers the vulnerable code path. Concurrently, a high-frequency background payload or routine swaps the validated resource with a malicious counterpart, such as replacing a legitimate file or symbolic link with a crafted payload just after the check passes but before the use operation executes.\nThe attack flow proceeds as follows: First, the attacker establishes local access to the target system. Second, the attacker identifies a vulnerable system call, utility, or daemon that handles resource validation asynchronously. Third, the attacker initiates the targeted operation while deploying a concurrent manipulation thread to intercept the execution window. Fourth, upon successfully winning the race condition, the system executes the malicious payload or accesses the unauthorized resource under the context of the running process.\nAuthentication requirements dictate that the attacker must possess local execution capabilities on the underlying operating system. Privilege requirements depend on the specific vulnerable component, but successful exploitation typically enables privilege escalation or arbitrary code execution within the security context of the affected process. Network exposure is absent, as the vector is entirely local. Post-exploitation impact includes full compromise of the affected local environment, potential execution of arbitrary system commands, and further degradation of system integrity."
}