Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to cause a denial of service and compromise data integrity due to a time-of-check time-of-use race condition.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.7",
  "pubDate": "2026-08-19T16:17:06.297Z",
  "pubdate": "2026-08-19T16:17:06.297Z",
  "executiveSummary": "This vulnerability involves a time-of-check time-of-use (TOCTOU) race condition affecting IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1. The flaw allows a local attacker to cause a denial of service and compromise data integrity on vulnerable systems. The risk implications are significant as unauthorized local manipulation of system files or shared resources can lead to application crashes, system instability, and unauthorized data modification. Exploitation requires local access to the target host and the ability to execute code, leveraging precise timing to win the race condition between the security validation check and the subsequent resource utilization phase. No network exposure is required for initial access, making this a localized threat vector typically driven by malicious local processes or compromised low-privilege user accounts seeking privilege escalation or service disruption.",
  "technicalDetails": "The root cause of the vulnerability stems from a time-of-check time-of-use (TOCTOU) race condition flaw inherent in how IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1 handle resource validation and access operations. Specifically, the vulnerable component performs a security or state verification check on a file or shared resource (the time of check) and subsequently accesses or modifies that same resource in a separate operational step (the time of use). Because these two actions are not executed atomically, a window of vulnerability exists between the check and the use operations. An attacker with local access can exploit this temporal gap by rapidly manipulating the targeted file system path or resource state during the execution window. By swapping the validated resource with a malicious payload or a symbolic link pointing to a critical system file after the check has passed but before the use occurs, the attacker bypasses intended security controls. This race condition leads directly to data integrity compromises, as unauthorized modifications are processed under the context of the executing application or kernel component, and can induce denial of service conditions by invalidating expected resource structures or causing unexpected execution faults. Successful exploitation requires local execution capabilities and precise timing synchronization to reliably intercept the operational window between the validation check and the resource consumption phase."
}