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 the use of an uninitialized variable.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-08-13T21:17:41.650Z",
  "pubdate": "2026-08-13T21:17:41.650Z",
  "executiveSummary": "This vulnerability involves a denial of service flaw affecting IBM i versions 7.6, 7.5, 7.4, and 7.3.\nThe core issue stems from the utilization of an uninitialized variable within the affected software components.\nAn unauthenticated remote attacker can exploit this condition by sending specially crafted requests or triggering specific execution paths that consume or evaluate the uninitialized memory space.\nThe primary impact of this vulnerability is system instability or service disruption, culminating in a denial of service state for the targeted IBM i environment.\nSuccessful exploitation does not inherently require prior authentication, broadening the attack surface to remote threat actors capable of network interaction with the vulnerable system.\nRisk implications include potential operational downtime, degradation of critical enterprise workloads, and loss of availability for services hosted on the IBM i platform.\nDefensive posture requires applying vendor-supplied software fixes and patches as soon as they become available, as well as enforcing strict network segmentation and boundary controls to limit exposure to untrusted networks.",
  "technicalDetails": "The vulnerability is rooted in a programming defect where a variable is declared or allocated in memory but is referenced or evaluated prior to being explicitly assigned a valid initial value.\nIn the context of IBM i 7.6, 7.5, 7.4, and 7.3, this uninitialized variable condition affects specific internal routines or subsystems responsible for processing network communications or client requests.\nWhen a remote attacker interacts with the vulnerable service, they can supply specific inputs or trigger execution sequences that cause the application logic to read the contents of the uninitialized variable.\nBecause the contents of uninitialized memory are indeterminate and depend entirely on previous memory allocations and states, processing this unpredictable value leads to unexpected program behavior.\nThis unexpected behavior typically manifests as a null pointer dereference, an invalid memory access exception, an unhandled trap, or a critical exception within the process space.\nThe resulting crash or abnormal termination of the affected service process immediately prevents legitimate users and dependent applications from accessing system capabilities, thereby achieving a denial of service condition.\nThe attack flow proceeds as follows: first, the remote attacker establishes a network connection to the vulnerable service exposed by the IBM i system; second, the attacker transmits a maliciously crafted payload designed to navigate the vulnerable code path; third, the application executes the routine containing the uninitialized variable; fourth, the runtime environment encounters the invalid state resulting from the uninitialized memory read; fifth, the process faults and terminates unexpectedly.\nNetwork exposure is a prerequisite for exploitation, as the vulnerable service must be reachable by the attacker over the network protocol utilized by the affected component.\nAuthentication and privilege requirements depend on the specific exposed interface, but the vulnerability profile indicates remote exploitability which may bypass standard authentication checks if the flaw resides in pre-authentication parsing routines or low-level protocol handlers.\nPost-exploitation impact is strictly confined to availability degradation, as the use of an uninitialized variable in this context primarily induces application faults rather than arbitrary code execution or unauthorized data disclosure."
}