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 a heap buffer overflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-13T20:17:17.377Z",
  "pubdate": "2026-08-13T20:17:17.377Z",
  "executiveSummary": "A heap buffer overflow vulnerability has been identified in IBM i versions 7.6, 7.5, 7.4, and 7.3.\nThis vulnerability allows a remote attacker to cause a denial of service condition on affected systems.\nThe flaw stems from improper bounds checking during the handling of input data, leading to memory corruption within the heap structure.\nSuccessful exploitation requires network access to the vulnerable service, enabling an unauthenticated or remote attacker to disrupt system availability by crashing critical processes or exhausting system resources.\nThe risk implications include unexpected system termination, service degradation, and potential operational downtime for enterprise environments relying on the affected IBM i operating system versions.\nNo specific privileges are explicitly detailed as prerequisites for triggering the heap corruption, heightening the operational risk for exposed network services.\nOrganizations utilizing the impacted software versions must apply vendor-supplied updates or implement appropriate network segmentation and perimeter controls to mitigate potential exploitation attempts against vulnerable endpoints.",
  "technicalDetails": "The vulnerability is classified as a heap buffer overflow, occurring when a program allocates a specific amount of memory on the heap but subsequently writes data that exceeds the allocated buffer size.\nIn the context of IBM i versions 7.6, 7.5, 7.4, and 7.3, the vulnerable component fails to adequately validate the length of incoming data before copying it into dynamically allocated heap memory buffers.\nThe root cause is a lack of rigorous boundary enforcement within the memory management and input processing routines.\nAn attacker initiates the attack flow by constructing a specially crafted network payload designed to exceed the expected data length parameters handled by the target service.\nUpon transmission over the network, the vulnerable service receives the oversized input and processes it through the flawed data handling function.\nAs the application writes the excessive data into the fixed-size heap buffer, adjacent memory structures, control blocks, or metadata pointers are overwritten.\nThis memory corruption disrupts the internal state of the heap allocator or overwrites critical application data structures.\nThe resulting corruption typically triggers an exception, segmentation fault, or immediate process termination as the operating system or runtime environment detects the invalid memory state.\nThis sequence directly results in a denial of service condition, rendering the affected service or subsystem unresponsive.\nDepending on the specific daemon or service hosting the vulnerable component, the crash may require administrative intervention to restart services or recover system stability.\nNetwork exposure is a prerequisite, as the attack vector is leveraged remotely without requiring prior local access or specific authentication credentials.\nThe exploitation method relies solely on the ability to send malformed packets to the listening service, causing destabilization of the underlying IBM i architecture across the specified product versions."
}