Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to execute arbitrary code due to a stack-based buffer overflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-12T20:17:39.260Z",
  "pubdate": "2026-08-12T20:17:39.260Z",
  "executiveSummary": "This vulnerability is classified as a stack-based buffer overflow affecting IBM i operating system versions 7.3, 7.4, 7.5, and 7.6. The flaw arises from improper bounds checking during the processing of input data within vulnerable components of the operating system. A remote attacker can exploit this weakness by sending specially crafted payloads to the target system, leading to memory corruption.\nSuccessful exploitation of this vulnerability allows a remote adversary to achieve arbitrary code execution with the privileges of the affected service or underlying process. This compromises the integrity, confidentiality, and availability of the targeted IBM i instance. The risk implications are severe, as arbitrary code execution can permit an attacker to install persistent malware, escalate privileges, or pivot deeper into enterprise infrastructure.\nThe attack capabilities require network connectivity to the vulnerable service on the target system. No authentication or elevated privileges are explicitly mentioned as prerequisites in the baseline description, implying that remote unauthenticated exploitation may be feasible depending on the specific network exposure of the vulnerable interface. Remediation requires applying official vendor patches or updates provided by IBM once available.",
  "technicalDetails": "The root cause of the vulnerability is a stack-based buffer overflow residing in input-handling routines within IBM i versions 7.3, 7.4, 7.5, and 7.6. Specifically, the affected software allocates a fixed-size buffer on the call stack to store incoming data parameters without adequately validating or restricting the length of the input supplied by the user or network peer.\nWhen an untrusted input stream exceeds the pre-allocated boundary of the stack buffer, the excess data overflows into adjacent memory regions on the stack. This results in the corruption of critical control data structures, most notably the saved frame pointer and the return instruction pointer. By carefully structuring the payload, an attacker can overwrite the return instruction pointer with a targeted memory address, redirecting the execution flow of the application to shellcode or a Return-Oriented Programming (ROP) gadget chain supplied within the input.\nThe step-by-step attack flow proceeds as follows: First, the remote attacker identifies the network exposure of the vulnerable service running on the IBM i host. Second, the attacker formulates a malicious payload engineered to fill the stack buffer and precisely overwrite the return address on the stack. Third, the attacker transmits this crafted payload over the network using the designated protocol to the target service. Fourth, the vulnerable component parses the input, triggering the buffer overflow condition as data is copied without bounds checking. Finally, upon function return, the CPU jumps to the attacker-controlled address, executing arbitrary code within the security context of the process.\nThe affected components are core OS libraries or network-facing daemons within IBM i 7.3, 7.4, 7.5, and 7.6. Network exposure depends on the specific daemon or service utilizing the vulnerable parsing logic. Post-exploitation impact includes full system compromise, execution of arbitrary system commands, unauthorized access to sensitive database environments hosted on the IBM i platform, and potential lateral movement across the connected corporate network."
}