CVE-2026-18020

Analyzed Analyzed - Analysis Complete

Denial of Service in IBM i Due to Off-by-One Error

Publication date: 2026-08-13

Last updated on: 2026-08-19

Assigner: IBM Corporation

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 an off-by-one error in bounds checking.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-13

Last Modified

2026-08-19

Generated

2026-09-03

AI Q&A

2026-08-14

EPSS Evaluated

2026-09-01

NVD

CVE-2026-18020

Affected Vendors & Products

Vendor	Product	Version / Range
ibm	i	7.3
ibm	i	7.4
ibm	i	7.5
ibm	i	7.6

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-125	The product reads data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This is a denial of service vulnerability in IBM i versions 7.6, 7.5, 7.4, and 7.3 caused by an off-by-one error in bounds checking. A remote attacker could exploit this to cause system instability or crash.

Detection Guidance

This vulnerability is specific to IBM i systems and involves an off-by-one error causing a denial of service. Detection requires checking IBM i system logs for unusual network traffic or service disruptions. Use IBM i commands like DSPLOG to review system logs for errors related to network services or applications. Monitor for crashes or hangs in network-facing applications.

Impact Analysis

The vulnerability allows remote attackers to disrupt services by causing a denial of service. This could lead to system unavailability, affecting business operations or services relying on IBM i systems.

Compliance Impact

This vulnerability is a denial of service issue caused by an off-by-one error in bounds checking. It does not directly impact data confidentiality or integrity, which are key focus areas for GDPR and HIPAA. However, prolonged service disruption could indirectly affect compliance by impairing system availability required for regulated operations.

Mitigation Strategies

Apply IBM i PTFs or updates provided by IBM to address the off-by-one error in bounds checking. Monitor IBM security advisories for patches and test updates in a non-production environment before deployment.

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