# CVE-2026-98859: HID: multitouch: stop the release timer from being rearmed on remove

> A use-after-free vulnerability in the Linux kernel HID multitouch driver allows local attackers to cause a system crash or potentially execute code via a race condition during device removal.

- **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:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-108818, BELL-CVE-2026-98859, DEBIAN-CVE-2026-98859, GHSA-rf84-p87x-87h6, UBUNTU-CVE-2026-98859

## What is CVE-2026-98859?

CVE-2026-98859 is an use after free vulnerability in Linux, published on 18 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:

HID: multitouch: stop the release timer from being rearmed on remove

mt_remove() quiesces the sticky-finger timer before stopping the
hardware:

    timer_delete_sync(&td->release_timer);

    sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
    hid_hw_stop(hdev);

timer_delete_sync() waits for a running callback and dequeues the timer,
but it does not stop the timer from being armed again. The transport is
still delivering reports at that point, and the report path rearms it:

    if (app->quirks & MT_QUIRK_STICKY_FINGERS) {
        if (td->mt_io_flags & MT_IO_SLOTS_MASK)
            mod_timer(&td->release_timer,
                      jiffies + msecs_to_jiffies(100));

A report that arrives after timer_delete_sync() has returned therefore
leaves the timer queued. td is allocated with devm_kzalloc() against
hdev->dev, so it is freed when the driver is unbound, after mt_remove()
returns. When the timer fires afterwards, mt_expired_timeout()
dereferences the freed td:

    struct mt_device *td = timer_container_of(td, t, release_timer);
    struct hid_device *hdev = td->hdev;

    if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))

Simply moving the teardown after hid_hw_stop() does not fix this on its
own, because mt_expired_timeout() calls mt_release_contacts(), which
walks hdev->inputs; the timer still has to be quiesced before
hid_hw_stop() tears the input devices down.

Use timer_shutdown_sync() instead, which additionally makes any later
mod_timer() a no-op, so neither ordering constraint has to be traded off
against the other. This is the final-teardown pattern the function was
introduced for, and hid-wiimote already uses it for the same reason.

## Which versions are affected by CVE-2026-98859?


## How do I fix CVE-2026-98859?

Apply the vendor's patch.

## Is CVE-2026-98859 being exploited?

There is no known exploitation of CVE-2026-98859 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98859 and fix it if it is affected.

What it is: CVE-2026-98859 is an use after free vulnerability in Linux, published on 18 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-2026-98859 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-2026-98859/ (Markdown: https://insights.sbomify.com/CVE-2026-98859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98859
- OSV: https://osv.dev/vulnerability/CVE-2026-98859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98859/
Summaries are generated and may contain mistakes; the official description above is the record.