# CVE-2025-21827: Bluetooth: btusb: mediatek: Add locks for usb_driver_claim_interface()

> A race condition in the Linux kernel Bluetooth driver can cause NULL pointer dereferences and system crashes due to missing locks.

- **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:** 6 Mar 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-21827, DEBIAN-CVE-2025-21827, GHSA-448g-f6xx-9xfw, UBUNTU-CVE-2025-21827

## What is CVE-2025-21827?

CVE-2025-21827 is a high-severity vulnerability in Linux kernel, published on 6 Mar 2025. 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:

Bluetooth: btusb: mediatek: Add locks for usb_driver_claim_interface()

The documentation for usb_driver_claim_interface() says that "the
device lock" is needed when the function is called from places other
than probe(). This appears to be the lock for the USB interface
device. The Mediatek btusb code gets called via this path:

  Workqueue: hci0 hci_power_on [bluetooth]
  Call trace:
   usb_driver_claim_interface
   btusb_mtk_claim_iso_intf
   btusb_mtk_setup
   hci_dev_open_sync
   hci_power_on
   process_scheduled_works
   worker_thread
   kthread

With the above call trace the device lock hasn't been claimed. Claim
it.

Without this fix, we'd sometimes see the error "Failed to claim iso
interface". Sometimes we'd even see worse errors, like a NULL pointer
dereference (where `intf->dev.driver` was NULL) with a trace like:

  Call trace:
   usb_suspend_both
   usb_runtime_suspend
   __rpm_callback
   rpm_suspend
   pm_runtime_work
   process_scheduled_works

Both errors appear to be fixed with the proper locking.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-21827?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21827?

Apply the vendor's patch.

## Is CVE-2025-21827 being exploited?

There is no known exploitation of CVE-2025-21827 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-2025-21827 and fix it if it is affected.

What it is: CVE-2025-21827 is a high-severity vulnerability in Linux kernel, published on 6 Mar 2025. 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-2025-21827 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-2025-21827/ (Markdown: https://insights.sbomify.com/CVE-2025-21827/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21827
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21827
- OSV: https://osv.dev/vulnerability/CVE-2025-21827

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21827/
Summaries are generated and may contain mistakes; the official description above is the record.