CVE-2026-17259 in IBM
Summary
by MITRE • 09/04/2026
IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote authenticated attacker to cause a denial of service due to a stack-based buffer overflow.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in IBM i operating system versions 7.6, 7.5, 7.4, and 7.3 represents a critical security flaw rooted in improper memory management within the application's processing logic. Specifically, this is classified as a stack-based buffer overflow, which occurs when a program writes more data to a fixed-length block of memory on the call stack than it can hold. In the context of IBM i, this defect allows an attacker who has already established authenticated access to exploit the flaw remotely. The presence of authentication requirements indicates that the vulnerability is not immediately exploitable by unauthenticated external actors over the public internet but poses a significant threat within trusted network environments or through compromised user credentials.
From a technical perspective, stack-based buffer overflows are particularly dangerous because they can lead to arbitrary code execution if exploited correctly, although in this specific instance, the primary reported impact is denial of service. When an attacker sends specially crafted input that exceeds the allocated buffer size on the stack, it corrupts adjacent memory locations, potentially overwriting critical control data such as return addresses or function pointers. This corruption disrupts the normal flow of execution within the operating system's processes. The immediate operational consequence is a crash or hang of the affected service or application, resulting in a denial of service condition where legitimate users are unable to access resources hosted on the compromised IBM i systems.
This vulnerability aligns with Common Weakness Enumeration (CWE) ID 120, which describes buffer copy without checking size limits, and more specifically CWE 121 for stack-based buffer overflow. In terms of offensive security frameworks like MITRE ATT&CK, this flaw facilitates techniques associated with Initial Access if authentication is bypassed or obtained through other means, but primarily it supports Denial of Service tactics under the Impact category. The ability to cause a denial of service remotely via authenticated access underscores the importance of strict input validation and bounds checking in software development practices for enterprise operating systems.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. IBM has likely released patches or updates that address this specific buffer overflow by implementing proper length checks before copying data to stack-allocated buffers. Administrators should prioritize applying the latest cumulative PTFs (Program Temporary Fixes) provided by IBM for their respective versions of IBM i 7.3 through 7.6. Additionally, network segmentation and strict access control lists can limit exposure by ensuring that only authorized personnel or systems with valid credentials can interact with vulnerable services. Implementing intrusion detection systems to monitor for anomalous traffic patterns indicative of buffer overflow attempts can also provide an additional layer of defense against exploitation attempts within the internal network infrastructure.