CVE-2026-16849 in AIX
Summary
by MITRE • 08/19/2026
IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a remote attacker to cause a denial of service due to an improper check for an array index boundary.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified in IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM Virtual I/O Server (VIOS) version 4.1, represents a critical memory safety flaw rooted in the failure to validate array indices before access operations are executed. This specific defect classifies under Common Weakness Enumeration identifier CWE-193, which describes an off-by-one error or improper calculation of array boundaries that leads to accessing memory outside the intended buffer limits. In the context of these IBM enterprise operating systems and virtualization platforms, such a flaw typically resides within low-level system services or kernel components responsible for handling network packets, configuration data, or internal state transitions. When a remote attacker crafts a malicious input payload containing an array index that exceeds the allocated memory bounds but is not properly checked by the application logic, the software proceeds to read from or write to unauthorized memory locations. This lack of boundary validation is a fundamental programming error that undermines the integrity and stability of the host system.
The operational impact of this vulnerability is primarily characterized by a denial of service condition rather than immediate remote code execution or privilege escalation, although the latter cannot be entirely ruled out depending on the specific memory layout and exploitation techniques employed. By triggering the improper array index check, an attacker can cause the affected process to crash, leading to system instability or complete unavailability of services hosted on the compromised AIX or PowerVM VIOS instance. For IBM AIX systems, this could disrupt critical business applications running in user space if they rely on vulnerable kernel interfaces. In the case of IBM PowerVM VIOS 4.1, which serves as a hypervisor managing virtual I/O resources for multiple logical partitions, a denial of service attack is particularly severe because it can isolate entire server environments from their storage and network resources. This effectively halts operations across all guest operating systems dependent on that specific Virtual I/O Server instance, resulting in significant downtime and potential data unavailability until the system is rebooted or patched.
From an offensive security perspective, this vulnerability aligns with MITRE ATT&CK technique T1498, specifically Network Denial of Service, where attackers target network services to disrupt availability. The exploitation vector requires remote access, meaning the attacker does not need local authentication on the target system but must be able to send crafted packets or requests to the vulnerable service endpoints exposed over the network. This makes the vulnerability particularly dangerous in internet-facing environments or within segmented networks where lateral movement is possible. The absence of proper input validation allows for automated exploitation tools to systematically probe and trigger the flaw, potentially leading to widespread outages if multiple systems are affected simultaneously without adequate mitigation controls such as rate limiting or intrusion prevention system rules that detect anomalous array access patterns.
To mitigate this risk, organizations running IBM AIX 7.2, 7.3, or PowerVM VIOS 4.1 must apply the latest security patches and maintenance updates provided by IBM. These updates typically include code changes that enforce strict bounds checking on all array operations, ensuring that any index value is validated against the maximum allowable size before memory access occurs. Administrators should also implement network segmentation strategies to limit exposure of vulnerable services to trusted networks only. Additionally, deploying intrusion detection systems with signatures capable of identifying malformed packets or unusual traffic patterns associated with buffer overflow attempts can provide an additional layer of defense in depth. Regular vulnerability scanning and patch management cycles are essential to ensure that such known weaknesses do not remain exploitable for extended periods, thereby maintaining the confidentiality, integrity, and availability of critical enterprise infrastructure.