CVE-2026-16924 in AIX
Summary
by MITRE • 08/20/2026
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 calculation of a memory offset during IPsec decapsulation.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in IBM AIX versions 7.2 and 7.3, as well as IBM PowerVM VIOS version 4.1, represents a critical flaw within the implementation of Internet Protocol Security (IPsec) processing logic. Specifically, this issue stems from an improper calculation of memory offsets during the decapsulation phase of IPsec packets. When a system receives encapsulated traffic that requires decryption and header removal to access the underlying payload, it must accurately calculate where in memory the new data structures should be placed or how much space is required for processing. In this specific instance, the software fails to correctly compute these offsets, leading to potential buffer overflows or out-of-bounds memory accesses. This type of error typically occurs when input validation is insufficient or when arithmetic operations involving packet lengths and header sizes are not properly bounded against available memory limits.
From a technical perspective, this flaw falls under the category of improper neutralization for special elements used in an expression, commonly known as CWE-134: Use of Externally-Controlled Format String, although more accurately it aligns with CWE-787: Out-of-bounds Write or CWE-125: Out-of-bounds Read depending on the exact nature of the memory corruption. The core issue lies in the kernel-level network stack handling of IPsec packets. If an attacker can craft a maliciously formatted IPsec packet that triggers this miscalculation, they may cause the operating system to write data beyond allocated buffer boundaries or read from invalid memory locations. This disruption in normal memory management is the primary vector for exploitation and directly impacts the stability of the host system running IBM AIX or PowerVM VIOS.
The operational impact of exploiting this vulnerability is primarily a denial of service (DoS). Because the flaw resides within the core network processing components, triggering it can cause the affected operating system to crash, hang, or become unresponsive. For systems like IBM PowerVM VIOS, which serve as critical infrastructure for managing virtualized environments on POWER hardware, such instability can lead to significant downtime and disruption of services hosted by multiple logical partitions. Even in standard AIX deployments, a successful exploitation could render the server inaccessible to legitimate users until it is rebooted or restarted. This makes the vulnerability particularly dangerous in production environments where high availability is required, as there may be no immediate workaround other than patching or restarting affected systems after an incident occurs.
In terms of threat modeling and industry standards, this vulnerability aligns with MITRE ATT&CK technique T1498: Network Denial of Service, specifically under the sub-technique related to resource exhaustion via protocol vulnerabilities. Attackers do not necessarily need elevated privileges or authentication credentials to exploit this flaw if IPsec is configured in a way that processes incoming traffic from untrusted networks without sufficient pre-filtering. The ability to remotely trigger a system crash highlights the severity of the issue, as it allows for low-effort disruption of critical IT infrastructure. Security teams should recognize this not just as an isolated bug but as part of a broader pattern where network stack implementations are prone to complex memory management errors that can be weaponized by remote adversaries.
To mitigate the risks associated with this vulnerability, organizations must ensure that all affected IBM AIX and PowerVM VIOS systems are updated with the latest security patches provided by IBM. These updates typically include corrections to the IPsec implementation logic that enforce proper bounds checking during memory offset calculations. Additionally, network segmentation strategies should be reviewed to limit exposure of these critical servers to untrusted networks where such malicious packets might originate. Implementing strict ingress filtering and deploying intrusion detection systems capable of identifying anomalous IPsec packet structures can provide an additional layer of defense against exploitation attempts while patch management processes are completed. Regular auditing of system logs for signs of kernel panics or unexpected reboots is also recommended to detect potential exploitation activities early in the attack lifecycle.