Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service due to an out-of-bounds write.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.6",
  "pubDate": "2026-08-13T21:17:43.677Z",
  "pubdate": "2026-08-13T21:17:43.677Z",
  "executiveSummary": "This vulnerability represents a critical security flaw affecting IBM i operating system versions 7.3, 7.4, 7.5, and 7.6. Specifically, the defect is classified as an out-of-bounds write vulnerability that can be leveraged by a remote attacker to induce a denial of service condition on targeted systems.\nThe primary impact of successful exploitation involves system instability, application crashes, and potential operational disruption of critical business services hosted on the affected IBM i platform. The risk implications are severe due to the potential for remote execution and disruption without requiring complex local access.\nAttacker capabilities include the ability to target vulnerable network-exposed components of the IBM i operating system remotely. Exploitation requirements involve sending maliciously crafted network packets or input data designed to trigger memory corruption via an out-of-bounds write operation within the vulnerable subsystem.\nOrganizations running the specified IBM i versions face significant availability risks if unpatched or unmitigated. Immediate remediation requires applying official vendor-supplied fixes and adhering to strict network segmentation to limit remote exposure.",
  "technicalDetails": "The root cause of this vulnerability stems from insufficient boundary checks and inadequate input validation during memory manipulation operations within the affected IBM i components. Specifically, an out-of-bounds write condition occurs when the application or operating system subsystem attempts to write data past the allocated boundaries of an internal buffer.\nThe vulnerable components reside within the network-facing services of IBM i versions 7.3, 7.4, 7.5, and 7.6. Because these services process untrusted input directly from remote network interfaces, they present an attractive attack vector for malicious actors seeking to compromise system availability.\nExploitation occurs remotely over the network. An unauthenticated or remotely authenticated attacker can initiate network communication with the vulnerable service and transmit a meticulously crafted payload designed to exceed the predetermined length of a memory buffer. As the target subsystem processes this malicious input, the lack of proper bounds checking allows the execution flow to overwrite adjacent memory regions.\nThe payload behavior during an out-of-bounds write typically corrupts critical stack or heap structures, leading immediately to memory access violations, segmentation faults, or abnormal termination of the affected daemon or the entire operating system kernel. This direct memory corruption manifests operationally as a denial of service.\nWhile the primary documented impact is a denial of service, memory corruption vulnerabilities of this nature theoretically carry the latent risk of arbitrary code execution if the attacker can precisely control the overwritten memory contents. However, the direct observable attack flow focuses on destabilizing the system availability.\nAuthentication and privilege requirements depend on the specific network service exposed, but the remote attack vector implies that network reachability to the vulnerable IBM i endpoint is the primary prerequisite. No specialized local privileges are required if the targeted service accepts unauthenticated remote connections."
}