# CVE-2026-98197: hwmon: (w83791d) remove fan/pwm 4-5 sysfs group on remove

> A use-after-free vulnerability in the Linux kernel w83791d driver allows attackers to access stale memory via sysfs files after driver unbinding.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106203, BELL-CVE-2026-98197, DEBIAN-CVE-2026-98197, GHSA-w8gm-245m-mgrg, UBUNTU-CVE-2026-98197

## What is CVE-2026-98197?

CVE-2026-98197 is a high-severity use after free vulnerability in Linux, published on 6 Oct 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:

hwmon: (w83791d) remove fan/pwm 4-5 sysfs group on remove

When the fan/pwm 4-5 pins are not used as GPIO, w83791d_probe()
creates the w83791d_group_fanpwm45 sysfs group on the I2C client
device.

The probe error path removes this group when a later initialization
step fails, but the normal remove path only removes w83791d_group.
As a result, the optional fan/pwm 4-5 sysfs files can remain after the
driver is unbound.

The callbacks associated with these files access the driver data,
which is devm allocated and released after driver unbind. Leaving the
sysfs files behind can therefore result in accesses to stale driver
data.

Remove w83791d_group_fanpwm45 during normal teardown as well.

This issue was found by manual code inspection.

## Which versions are affected by CVE-2026-98197?


## How do I fix CVE-2026-98197?

Apply the vendor's patch.

## Is CVE-2026-98197 being exploited?

There is no known exploitation of CVE-2026-98197 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98197 and fix it if it is affected.

What it is: CVE-2026-98197 is a high-severity use after free vulnerability in Linux, published on 6 Oct 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-2026-98197 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-2026-98197/ (Markdown: https://insights.sbomify.com/CVE-2026-98197/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98197
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98197
- OSV: https://osv.dev/vulnerability/CVE-2026-98197

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98197/
Summaries are generated and may contain mistakes; the official description above is the record.