Expected behavior violation in Linux kernel - CVE-2026-89459
Published: September 12, 2026
Vulnerability identifier: #VU149355
CSH Severity: Low
CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89459
CWE-ID: CWE-440
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to prevent the exception return path from repairing the per-CPU address register after migration.
The vulnerability exists due to incorrect assembler macro argument construction in MVIY_PERCPU() when building s390 kernel code with GNU as versions prior to binutils 2.39. A local user can trigger an interrupted per-CPU sequence that migrates between CPUs to prevent the exception return path from repairing the per-CPU address register after migration.
The omitted mviy instruction leaves the interrupted per-CPU sequence unmarked in lowcore.
Affected software
Linux kernel
How to mitigate CVE-2026-89459
Install security update from vendor's repository.