Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a local attacker to cause a denial of service due to a stack-based buffer overflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-09-04T17:16:53.400Z",
  "pubdate": "2026-09-04T17:16:53.400Z",
  "executiveSummary": "A stack-based buffer overflow vulnerability exists within IBM i versions 7.3, 7.4, 7.5, and 7.6. This vulnerability permits a local attacker to trigger a denial of service (DoS) condition by manipulating input data passed to an affected process.\nThe vulnerability originates from improper bounds checking on user-supplied input, leading to a memory corruption event when data exceeds the allocated stack buffer space. By providing specially crafted input, an attacker can overwrite adjacent memory locations on the execution stack, leading to process instability or an application crash.\nAs this is a local attack vector, the threat actor must already possess authenticated access to the system environment. The primary risk implication is the degradation or total cessation of system service, which may disrupt critical business operations reliant on the IBM i platform. There is no indication of remote exploitability; therefore, the vulnerability is constrained to users with local login capabilities or those who can influence the local execution flow of vulnerable processes.",
  "technicalDetails": "The vulnerability is characterized as a stack-based buffer overflow occurring within the IBM i operating system environments across versions 7.3, 7.4, 7.5, and 7.6. The root cause is the failure of the application or system utility to perform adequate validation of the size of incoming data before writing it to a fixed-size buffer allocated on the thread stack.\nDuring the execution flow, if a process or system service receives input that exceeds the bounds of the destination buffer, the surplus data overflows the allocated memory space. In the context of stack-based buffers, this leads to the corruption of adjacent memory structures, which may include function return addresses, saved frame pointers, or local variables. When the execution flow eventually references these corrupted structures, the processor encounters an invalid instruction or memory address, triggering an exception that forces the process to terminate.\nFrom an exploitation perspective, a local attacker leverages this vulnerability by injecting a payload designed to exceed the intended buffer length. Because this requires local access, the attacker is assumed to have an established session on the IBM i system. The attack flow involves identifying a vulnerable entry point—typically a service or utility accepting user input—and supplying a structured input string designed to overflow the stack frame upon processing. By precisely overwriting the return address with unexpected or invalid values, the attacker induces a crash.\nThe scope of this vulnerability encompasses the core system components of IBM i. Since the buffer overflow occurs within the memory space of the affected process, the resulting denial of service is limited to the functionality provided by that specific process, or if the process is critical to system stability, the entire partition. The lack of proper bounds checking is a fundamental flaw in the memory management handling of the affected code segments. Post-exploitation impact is primarily limited to system unavailability; however, if the overflow allows for control flow redirection, theoretical execution of arbitrary code may be possible depending on memory protections such as Data Execution Prevention (DEP) or Address Space Layout Randomization (ASLR) implemented within the IBM i architecture. Current assessment confirms that the primary observable outcome is a disruption of services."
}