CVE-2026-17068 in IBM
Summary
by MITRE • 10/16/2026
IBM i 7.3, 7.4, 7.5, and 7.6 could allow a local attacker to bypass NFS version restrictions due to improper enforcement of the export version flag.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in IBM i versions 7.3 through 7.6 stems from an insufficient validation mechanism within the Network File System implementation. Specifically, the operating system fails to strictly enforce the export version flags when processing requests for NFS shares. This architectural flaw allows a local attacker who has already gained access to the system to manipulate how NFS exports are interpreted and served. The core issue lies in the improper enforcement of configuration parameters that dictate which versions of the NFS protocol are permitted, creating a gap between intended security policy and actual runtime behavior.
From a technical perspective, this defect represents a classic case of insecure direct object reference or logic error within system-level file sharing services. By exploiting the lack of strict flag validation, an attacker can potentially force the NFS server to operate in modes that were explicitly disabled by administrators. This bypass effectively neutralizes security controls designed to restrict access based on protocol versioning, which is often used as a defense-in-depth measure against known vulnerabilities present in older or less secure versions of the NFS standard.
The operational impact of this vulnerability is significant for environments relying on strict network isolation and controlled file sharing protocols. An attacker with local privileges could leverage this flaw to enable access via outdated or insecure NFS protocol versions, such as NFSv2 or early iterations of NFSv3, which may lack modern authentication mechanisms or encryption capabilities. This expansion of the attack surface allows for potential unauthorized data exfiltration, integrity violations, or further lateral movement within a network that assumes these older protocols are disabled and inaccessible.
This vulnerability aligns with CWE-284, Improper Access Control, as it involves the failure to restrict access to resources based on defined security policies. Furthermore, in the context of the MITRE ATT&CK framework, this behavior relates to techniques involving privilege escalation or defense evasion through misconfiguration exploitation. The attacker utilizes existing local privileges to alter service behavior, thereby evading intended restrictions and expanding their ability to interact with networked file systems without proper authorization checks.
To mitigate this risk, administrators should ensure that all affected IBM i systems are updated to the latest available fix levels provided by IBM, which address the validation logic within the NFS subsystem. Additionally, organizations should implement strict firewall rules to limit access to NFS ports from untrusted networks and regularly audit system configurations to verify that only approved protocol versions are enabled. Monitoring logs for unusual NFS activity can also help detect attempts to exploit this misconfiguration before significant damage occurs.