Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a remote attacker to execute arbitrary code due to a format string vulnerability.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-20T22:17:13.017Z",
  "pubdate": "2026-08-20T22:17:13.017Z",
  "executiveSummary": "A format string vulnerability exists within IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1, potentially allowing a remote attacker to execute arbitrary code on vulnerable systems.\nThe vulnerability arises from improper handling of format string arguments within the affected software components, enabling malicious actors to manipulate memory structures.\nSuccessful exploitation of this security flaw can lead to remote code execution, compromising the confidentiality, integrity, and availability of the underlying operating system and virtualized environments.\nAttackers with network access can leverage this flaw to interact with vulnerable services, injecting crafted format specifiers into logging or output functions.\nGiven the core nature of the affected operating systems and virtualization infrastructure, the risk implications are severe, demanding immediate attention from system administrators.\nMitigation requires applying official vendor patches and adhering to strict network exposure controls to prevent unauthorized remote interactions with vulnerable endpoints.",
  "technicalDetails": "The root cause of the vulnerability stems from insecure programming practices where user-supplied input is directly passed as the format parameter to standard output formatting functions, such as printf or syslog family functions, without proper sanitization or validation.\nThis flaw represents a classic format string vulnerability, where an attacker can supply format specifiers like %n, %x, or %s to read from and write to arbitrary memory locations.\nThe vulnerable components reside within specific daemons or communication interfaces of IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM VIOS version 4.1.\nExploitation occurs when an unauthenticated or remotely authenticated attacker crafts a malicious payload containing format string specifiers and transmits it over the network to the vulnerable service.\nUpon ingestion, the vulnerable function interprets the attacker-controlled input as format arguments, allowing the adversary to inspect stack memory, leak sensitive memory addresses to bypass defenses such as Address Space Layout Randomization (ASLR), and overwrite critical memory pointers.\nBy strategically leveraging the %n format specifier, an attacker can write arbitrary values to targeted memory addresses, subsequently redirecting execution flow to shellcode or leveraging Return-Oriented Programming (ROP) chains.\nThe attack flow proceeds with the initial network transmission, parsing of the malformed input by the vulnerable component, memory corruption via format string abuse, and ultimately the execution of arbitrary code with the privileges of the compromised process.\nDepending on the execution context of the vulnerable service, post-exploitation impact can range from local privilege escalation to complete system takeover of the AIX LPAR or the PowerVM VIOS management partition."
}