Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow an authenticated attacker to force a NetServer server thread exception, caused by an integer overflow during bounds checking in request processing. The attacker could exploit this vulnerability to cause a temporary denial of service.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-08-13T21:17:45.400Z",
  "pubdate": "2026-08-13T21:17:45.400Z",
  "executiveSummary": "An integer overflow vulnerability exists in the NetServer component of IBM i versions 7.6, 7.5, 7.4, and 7.3, potentially leading to a denial of service condition. The flaw arises from improper bounds checking during the parsing and processing of client requests, specifically resulting in an integer overflow that forces a server thread exception.\nThe primary impact of this vulnerability is a temporary denial of service against the targeted NetServer service, disrupting file and print sharing capabilities for legitimate users. Successful exploitation requires an authenticated attacker with network access to interact with the NetServer component.\nThe attacker must possess valid authentication credentials to establish a session and submit maliciously crafted requests designed to trigger the boundary calculation error. No privilege escalation or remote code execution capabilities are granted through this specific vector, as the direct consequence is restricted to thread termination and localized service disruption.\nRisk implications include potential operational downtime for dependent file and print operations on the affected IBM i systems. Organizations utilizing the impacted versions must evaluate their exposure and apply available vendor supplied fixes or workarounds to maintain service availability and integrity.",
  "technicalDetails": "The vulnerability resides within the NetServer request processing subsystem of IBM i versions 7.6, 7.5, 7.4, and 7.3. The root cause of the issue is an integer overflow condition that occurs during explicit bounds checking routines when the application validates incoming request lengths or offsets.\nDuring standard protocol handling, the NetServer component calculates buffer sizes and memory offsets to process incoming client payloads. If an authenticated attacker supplies carefully manipulated request parameters designed to exceed standard numerical boundaries, an integer overflow is triggered within the size calculation logic.\nThe attack flow proceeds as follows: First, the authenticated attacker establishes a network connection to the NetServer service running on the targeted IBM i host. Second, the attacker transmits a specially crafted request containing boundary parameters engineered to induce an integer overflow during the internal validation phase. Third, the bounds checking mechanism fails to accurately evaluate the oversized or wrapped integer value, allowing the execution flow to proceed with invalid memory offsets or buffer allocations.\nThis calculation failure immediately results in an unhandled exception within the specific NetServer server thread handling the request. The resultant thread exception forces the termination of the affected thread, culminating in a temporary denial of service for clients attempting to utilize that specific server process or session.\nPrerequisites for exploitation include network exposure to the NetServer service and valid authentication credentials to interact with the IBM i environment. The vulnerability is strictly confined to a denial of service impact, with no evidence of memory corruption leading to arbitrary code execution or unauthorized data disclosure based on the provided vulnerability scope."
}