Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service and compromise integrity due to a buffer overflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-04T17:16:53.020Z",
  "pubdate": "2026-09-04T17:16:53.020Z",
  "executiveSummary": "A buffer overflow vulnerability has been identified within IBM i versions 7.3, 7.4, 7.5, and 7.6. This memory corruption flaw permits a remote, unauthenticated attacker to trigger a denial of service (DoS) condition or potentially compromise the integrity of the affected system.\nThe vulnerability stems from improper bounds checking when processing inputs, allowing an attacker to supply data that exceeds allocated buffer capacity. This leads to unauthorized memory modification, which can crash system services or facilitate the execution of arbitrary code, depending on the memory layout and specific exploit implementation.\nThe risk implication is significant as it affects the core operating system environment, potentially impacting critical business operations that rely on IBM i for data processing and enterprise resource management.\nExploitation requires network connectivity to the target IBM i instance. By sending a specially crafted packet or request, the attacker can overflow the target buffer. Security teams should prioritize patching cycles and implement network-level access controls to minimize exposure until official vendor updates are applied.",
  "technicalDetails": "The vulnerability is characterized as a classic buffer overflow, where the system fails to validate the length of input data before copying it into a fixed-size memory buffer. This occurs within the underlying service responsible for handling incoming remote requests. When the input exceeds the buffer size, the excessive data overflows into adjacent memory regions.\nIn the context of IBM i, this memory corruption can result in the overwriting of critical control structures, such as return addresses or function pointers. By controlling these pointers, an attacker may redirect the execution flow of the application. The attack flow begins with the attacker identifying the target service port, followed by the delivery of a malicious payload designed to surpass the buffer's designated boundaries.\nIf the overflow occurs in a privileged context, the attacker may gain the ability to manipulate the system state, leading to a loss of integrity. Alternatively, if the payload causes an invalid memory access, the system service will terminate abruptly, resulting in a denial of service condition. This is particularly dangerous for IBM i systems, which are often used for high-availability database and transaction processing.\nThe affected versions include 7.3, 7.4, 7.5, and 7.6. The exploitation process involves several stages: identification of a vulnerable interface, development of a payload that precisely targets the stack or heap structure of the service, and the delivery of this payload over the network. Because the vulnerability is exploitable remotely, it bypasses the need for local interaction, significantly increasing the potential attack surface. Once the overflow triggers, the system may exhibit instability, memory corruption errors, or an immediate crash, rendering the service unresponsive to legitimate users.\nFurthermore, because IBM i utilizes an integrated architecture, a compromise of a core system component may have cascading effects, potentially exposing sensitive data stored in DB2 or other middleware components. Successful exploitation requires an understanding of the service's memory management and the specific protocol involved to ensure the overflow reaches the intended target area without triggering security protections like Address Space Layout Randomization (ASLR) or Data Execution Prevention (DEP), if applicable."
}