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CVE-2026-18835 is a critical OS command injection vulnerability affecting IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM VIOS version 4.1. The vulnerability stems from improper neutralization of special elements used in an OS command, a weakness classified under CWE-78. This allows a remote authenticated attacker to execute arbitrary commands on the affected system.
The core issue lies in how the affected components handle externally-influenced input when constructing OS commands. The software fails to properly neutralize or sanitize special characters—such as ;, |, &, $(), and backticks—that can modify the intended command structure. An authenticated attacker with low privileges can exploit this by injecting malicious payloads into input fields that are later passed to the operating system shell for execution.
According to the CVSS v3.1 vector provided by IBM, the vulnerability has a base score of 9.9 (CRITICAL) with the vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. This indicates that the attack can be launched remotely over a network (AV:N), requires low attack complexity (AC:L), and needs only low-privileged credentials (PR:L). No user interaction is required (UI:N), and the scope is changed (S:C), meaning the vulnerability can affect resources beyond the vulnerable component. The impact on confidentiality, integrity, and availability is all rated as High (C:H/I:H/A:H). The vulnerability is classified as “very critical”.
The attack is considered easy to exploit. However, as of the latest reports, neither technical details nor a public exploit are available. The estimated price for an exploit on the black market ranges from approximately $5,000 to $25,000 USD. The MITRE ATT&CK technique associated with this vulnerability is T1202. IBM released an advisory and security update on August 20, 2026.
DailyCVE Form:
Platform: IBM AIX, PowerVM VIOS
Version: 7.2, 7.3, 4.1
Vulnerability: OS Command Injection
Severity: Critical (9.9)
Date: August 20, 2026
Prediction: Patch available August 2026
What Undercode Say:
Check AIX version oslevel -s Check VIOS version ioslevel Check for installed fixes related to the advisory instfix -ivk | grep -i "CVE-2026-18835" Check if the system is vulnerable by testing command injection (Educational Purpose Only - Do not run on production systems) Example: Injecting a harmless command like 'id' into a vulnerable parameter curl -X POST "https://target/vulnerable-endpoint" -d "input=value; id"
Exploit: (Educational Purposes!)
A remote authenticated attacker could exploit this vulnerability by injecting malicious OS commands into input fields that are not properly sanitized. For example, if an application passes user-supplied input directly to a system shell, an attacker could supply a payload such as `; malicious_command` to execute arbitrary commands with the privileges of the application. The attack requires low-privileged credentials and can be launched remotely over the network. No public exploit code is currently available.
Protection:
IBM has released security updates to address this vulnerability. Affected organizations should immediately apply the patches available from IBM support. The fixed versions include AIX 7.2 and 7.3 service packs and PowerVM VIOS 4.1.0.50 and 4.1.1.30 or later. As a mitigation, organizations should restrict access to affected systems, enforce the principle of least privilege, and monitor for suspicious command execution activities.
Impact:
Successful exploitation allows an attacker to execute arbitrary commands on the target system, leading to complete compromise of confidentiality, integrity, and availability. An attacker could install malware, exfiltrate sensitive data, create backdoors, or disrupt operations. Given the critical nature of AIX and PowerVM VIOS in enterprise environments, this vulnerability poses a severe risk to affected infrastructure.
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Sources:
Reported By: nvd.nist.gov
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