CVE-2026-89457 s390/dasd: Guard sysfs discipline callbacks against unallocated private data
An unprivileged local user can trigger a kernel panic by reading specific sysfs attributes during device initialization, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89457?
CVE-2026-89457 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
s390/dasd: Guard sysfs discipline callbacks against unallocated private data
Several sysfs show/store handlers call a discipline callback that dereferences device->private, either directly or through the DASD_DEFINE_ATTR() macro. During dasd_generic_set_online() the discipline is assigned before check_device() allocates device->private, so an unprivileged read of one of these world-readable attributes in that window dereferences a NULL pointer and panics.
Guard the dereference inside each callback that actually touches device->private.
Which versions are affected by CVE-2026-89457?
How do I fix CVE-2026-89457?
Apply the vendor's patch.
Is CVE-2026-89457 being exploited?
There is no known exploitation of CVE-2026-89457 in the wild and no public exploit code.
Sources
Also known as AZL-100304, BELL-CVE-2026-89457, DEBIAN-CVE-2026-89457, GHSA-94gp-p6v7-5m5q, UBUNTU-CVE-2026-89457.