# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100304, BELL-CVE-2026-89457, DEBIAN-CVE-2026-89457, GHSA-94gp-p6v7-5m5q, UBUNTU-CVE-2026-89457

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89457 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-89457 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89457/ (Markdown: https://insights.sbomify.com/CVE-2026-89457/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89457
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89457
- OSV: https://osv.dev/vulnerability/CVE-2026-89457

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89457/
Summaries are generated and may contain mistakes; the official description above is the record.