Executive brief
IBM i is an enterprise operating system used by many organizations to run critical business applications. A flaw in how the system handles symbolic links creates a race condition that allows an authenticated attacker to bypass access controls and gain unauthorized access to protected system objects, potentially leading to data theft, system compromise, or denial of service.
Technical details
A time-of-check time-of-use (TOCTOU) race condition in IBM i's symbolic link handling allows an authenticated network attacker to bypass authorization checks and access system objects they should not be permitted to access. The vulnerability occurs because the system checks permissions at one point in time, but an attacker can swap a symbolic link between the check and the actual file access. The attack requires authenticated access (PR:L), has high complexity (AC:H), but can result in complete confidentiality, integrity, and availability compromise across security boundaries (S:C). IBM has released PTFs (Program Temporary Fixes) for all affected versions (7.3, 7.4, 7.5, and 7.6).
Affected products
- IBM i 7.3 7.3
- IBM i 7.4 7.4
- IBM i 7.5 7.5
- IBM i 7.6 7.6
Timeline
- 2026-08-11: disclosed: IBM Security Bulletin initially published
- 2026-08-13: other: Advisory published (CVE-2026-16967)