Stack-Based Buffer Overflow in IBM i JSSE Provider

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 a local authenticated attacker to generate a stack-based buffer overflow in the Native IBM i JSSE provider, caused by improper bounds checking during TLS session establishment. A local attacker could overflow a fixed-length buffer and execute arbitrary code on the system or cause the JVM process to crash.

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-2026-18511

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-787	The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This is a stack-based buffer overflow vulnerability in IBM i systems (versions 7.6, 7.5, 7.4, and 7.3). It occurs in the Native IBM i JSSE provider during TLS session establishment due to improper bounds checking. A local authenticated attacker could exploit this to overflow a fixed-length buffer, potentially executing arbitrary code or crashing the JVM process.

Impact Analysis

If exploited, this vulnerability could allow a local attacker to run malicious code on your IBM i system or cause the Java Virtual Machine (JVM) to crash. This could lead to unauthorized access, data breaches, or system instability. Since it requires local authentication, remote attackers cannot exploit it directly.

Mitigation Strategies

Apply IBM i PTFs or updates provided by IBM to fix the Native IBM i JSSE provider buffer overflow issue. Monitor IBM i support channels for patches and test them in a non-production environment before full deployment.

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