IBM i NetServer Integer Overflow DoS Vulnerability

Publication date: 2026-08-13

Last updated on: 2026-08-13

Assigner: IBM Corporation

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-13

Last Modified

2026-08-13

Generated

2026-08-14

AI Q&A

2026-08-14

EPSS Evaluated

N/A

NVD

CVE-2026-18671

Affected Vendors & Products

Vendor	Product	Version / Range
ibm	ibm_i	From 7.6 (inc)
ibm	ibm_i	From 7.5 (inc)
ibm	ibm_i	From 7.4 (inc)
ibm	ibm_i	From 7.3 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-190	The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer overflow issue in IBM i NetServer request processing. An authenticated attacker can trigger an exception in server threads by sending specially crafted requests that cause the overflow during bounds checking. This leads to a temporary denial of service as the server becomes unresponsive.

Impact Analysis

If you use IBM i systems with NetServer enabled, an attacker could exploit this to disrupt services. This may cause temporary unavailability of file sharing or network services, affecting productivity and user access to shared resources.

Mitigation Strategies

Apply IBM i PTFs or updates provided by IBM to address the integer overflow issue in NetServer request processing. Monitor IBM security advisories for patches and test them in a non-production environment before deployment.

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