Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to overwrite arbitrary files due to improper resolution of symbolic links.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-20T22:17:15.247Z",
  "pubdate": "2026-08-20T22:17:15.247Z",
  "executiveSummary": "This security advisory addresses an arbitrary file overwrite vulnerability stemming from the improper resolution of symbolic links within affected IBM products. The flaw enables a local threat actor to manipulate file system operations, resulting in the unauthorized modification or destruction of critical system files. The vulnerability specifically impacts IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM VIOS version 4.1. The primary risk implication involves the potential escalation of privileges or localized denial of service by tampering with sensitive system binaries, configuration files, or log destinations. Successful exploitation requires local access to the target host and presupposes that the attacker possesses authenticated execution capabilities within the operating system environment. While remote exploitation is not facilitated by this vector, local privilege boundaries can be compromised if system utilities or administrative scripts insecurely handle file creation or symbolic link resolution in targeted directories.",
  "technicalDetails": "The root cause of the vulnerability lies in insecure file handling logic, specifically the improper resolution of symbolic links during file creation, modification, or administrative routines executed within IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1. When privileged or setuid/setgid utilities interact with the file system without securely validating destination paths or adequately handling pre-existing symbolic links, a Race Condition or Time-of-Check to Time-of-Use (TOCTOU) flaw may manifest.\nIn a typical attack flow, a local, authenticated attacker leverages their access to plant a symbolic link pointing to a critical system file (such as /etc/passwd, kernel modules, or core system binaries) within a directory where privileged processes subsequently write output, logs, or temporary files. Because the vulnerable component fails to adequately verify whether the target destination resolves to a symbolic link, the process blindly follows the link and writes data to the referenced arbitrary file with the privileges of the executing process.\nThe vulnerability requires local access and specific user execution privileges to establish the malicious symbolic link structures in designated vulnerable paths. The network exposure is negligible as the flaw cannot be triggered remotely without prior local shell access or execution vectors. Post-exploitation impact encompasses localized denial of service via truncation of critical configuration files, potential privilege escalation if writable system binaries are targeted, and integrity compromise of the underlying operating system environment."
}