# CVE-2026-46213: HID: appletb-kbd: fix UAF in inactivity-timer cleanup path

> A use-after-free vulnerability in the Linux kernel's Apple Touch Bar keyboard driver allows attackers to cause memory corruption or system crashes via race conditions during device teardown.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** 28 May 2026
- **Updated:** 14 Jun 2026
- **Also known as:** BELL-CVE-2026-46213, DEBIAN-CVE-2026-46213, GHSA-gmvx-6pfp-7mcv, UBUNTU-CVE-2026-46213

## What is CVE-2026-46213?

CVE-2026-46213 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 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: appletb-kbd: fix UAF in inactivity-timer cleanup path

Commit 38224c472a03 ("HID: appletb-kbd: fix slab use-after-free bug in
appletb_kbd_probe") added timer_delete_sync(&kbd->inactivity_timer) to
both the probe close_hw error path and appletb_kbd_remove(), but the
way it was wired in left the inactivity timer reachable during driver
tear-down via two distinct windows.

Window A -- put_device() before timer_delete_sync():

	put_device(&kbd->backlight_dev->dev);
	timer_delete_sync(&kbd->inactivity_timer);

The inactivity_timer softirq reads kbd->backlight_dev and calls
backlight_device_set_brightness() -> mutex_lock(&ops_lock).  If a
concurrent hid_appletb_bl unbind drops the last devm reference
between these two calls, the backlight_device is freed and the
mutex_lock() touches freed memory.

Window B -- backlight cleanup before hid_hw_stop():

	if (kbd->backlight_dev) {
		timer_delete_sync(...);
		put_device(...);
	}
	hid_hw_close(hdev);
	hid_hw_stop(hdev);

Even after Window A is closed, hid_hw_close()/hid_hw_stop() still run
afterwards, so a late ".event" callback from the HID core (USB URB
completion on real Apple hardware) can arrive after
timer_delete_sync() drained the softirq but before put_device() drops
the reference.  That callback reaches reset_inactivity_timer(), which
calls mod_timer() and re-arms the timer.  The freshly re-armed timer
can then fire on the about-to-be-freed backlight_device.

Both windows produce the same KASAN slab-use-after-free:

  BUG: KASAN: slab-use-after-free in __mutex_lock+0x1aab/0x21c0
  Read of size 8 at addr ffff88803ee9a108 by task swapper/0/0
  Call Trace:
   <IRQ>
   __mutex_lock
   backlight_device_set_brightness
   appletb_inactivity_timer
   call_timer_fn
   run_timer_softirq
   handle_softirqs
  Allocated by task N:
   devm_backlight_device_register
   appletb_bl_probe
  Freed by task M:
   (concurrent hid_appletb_bl unbind path)

Close both windows at once by reworking the tear-down in
appletb_kbd_remove() and in the probe close_hw error path so that

 1) hid_hw_close()/hid_hw_stop() run before the backlight cleanup,
    guaranteeing no further .event callback can fire and re-arm the
    timer, and
 2) inside the "if (kbd->backlight_dev)" block, timer_delete_sync()
    runs before put_device(), so the softirq is drained before the
    final reference is dropped.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46213?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46213?

Apply the vendor's patch.

## Is CVE-2026-46213 being exploited?

There is no known exploitation of CVE-2026-46213 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46213 and fix it if it is affected.

What it is: CVE-2026-46213 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 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-2026-46213 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46213/ (Markdown: https://insights.sbomify.com/CVE-2026-46213/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46213
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46213
- OSV: https://osv.dev/vulnerability/CVE-2026-46213

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46213/
Summaries are generated and may contain mistakes; the official description above is the record.