Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service and obtain sensitive information due to an integer underflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.2",
  "pubDate": "2026-08-12T22:17:14.433Z",
  "pubdate": "2026-08-12T22:17:14.433Z",
  "executiveSummary": "An integer underflow vulnerability has been identified in IBM i versions 7.6, 7.5, 7.4, and 7.3. This security flaw enables a remote attacker to trigger a denial of service condition and potentially disclose sensitive system information.\nThe vulnerability type stems from improper arithmetic boundary validation, specifically an integer underflow condition within the affected software components. When successfully exploited, the flaw compromises both system availability and confidentiality.\nAffected systems encompass IBM i deployments running versions 7.3, 7.4, 7.5, and 7.6. The risk implications are severe, as successful exploitation disrupts critical operations and exposes confidential data to unauthorized entities.\nThe attacker capabilities required to leverage this vulnerability include remote network access. The attacker can interact with the vulnerable service over the network to supply specially crafted inputs that trigger the underlying arithmetic error.\nSpecific authentication requirements and granular exploitation prerequisites depend on the targeted network service, but the flaw fundamentally allows unauthenticated or authenticated remote threat actors to destabilize the operating environment and extract protected data structures.",
  "technicalDetails": "The root cause of the vulnerability is an integer underflow condition within the arithmetic handling routines of the affected IBM i components. Specifically, when processing input data that dictates size calculations, memory offsets, or buffer boundaries, the application fails to adequately validate input values prior to performing arithmetic operations.\nWhen a specially crafted input is provided, the resulting calculation drops below the minimum representable value for the integer type, wrapping around to an unexpectedly large positive value or causing invalid memory management states.\nThe attack flow proceeds as follows: First, the remote attacker establishes a network connection to the vulnerable service running on IBM i versions 7.3, 7.4, 7.5, or 7.6. Second, the attacker transmits a malicious payload containing crafted parameters designed to provoke the integer underflow during internal data parsing or memory allocation routines.\nThird, the vulnerable component processes the manipulated input, resulting in an integer underflow. Fourth, the anomalous integer value propagates into subsequent memory operations or resource allocation functions, causing memory corruption, application crashes, or out-of-bounds read conditions.\nThe post-exploitation impact includes the abrupt termination of critical system services, directly inducing a denial of service condition that halts operations. Furthermore, the out-of-bounds read capability stemming from the calculation error allows the attacker to inspect adjacent memory regions, potentially leaking sensitive information such as system configurations, internal memory structures, or residual data from other processes.\nNetwork exposure is present across the affected versions, allowing remote exploitation paths without requiring physical access. Privilege requirements and authentication constraints vary based on the specific network protocol or daemon handling the vulnerable input vector, but the architectural flaw persists across IBM i 7.3, 7.4, 7.5, and 7.6 environments lacking the appropriate vendor-supplied fixes."
}