# CVE-2026-23146: Bluetooth: hci_uart: fix null-ptr-deref in hci_uart_write_work

> A race condition in the Linux kernel Bluetooth driver causes a null pointer dereference, leading to a system crash.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 14 Feb 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-23146, DEBIAN-CVE-2026-23146, GHSA-hcr8-x92w-q652, ROOT-OS-UBUNTU-2204-CVE-2026-23146, ROOT-OS-UBUNTU-2404-CVE-2026-23146, UBUNTU-CVE-2026-23146

## What is CVE-2026-23146?

CVE-2026-23146 is a medium-severity vulnerability in Linux kernel, published on 14 Feb 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:

Bluetooth: hci_uart: fix null-ptr-deref in hci_uart_write_work

hci_uart_set_proto() sets HCI_UART_PROTO_INIT before calling
hci_uart_register_dev(), which calls proto->open() to initialize
hu->priv. However, if a TTY write wakeup occurs during this window,
hci_uart_tx_wakeup() may schedule write_work before hu->priv is
initialized, leading to a NULL pointer dereference in
hci_uart_write_work() when proto->dequeue() accesses hu->priv.

The race condition is:

  CPU0                              CPU1
  ----                              ----
  hci_uart_set_proto()
    set_bit(HCI_UART_PROTO_INIT)
    hci_uart_register_dev()
                                    tty write wakeup
                                      hci_uart_tty_wakeup()
                                        hci_uart_tx_wakeup()
                                          schedule_work(&hu->write_work)
      proto->open(hu)
        // initializes hu->priv
                                    hci_uart_write_work()
                                      hci_uart_dequeue()
                                        proto->dequeue(hu)
                                          // accesses hu->priv (NULL!)

Fix this by moving set_bit(HCI_UART_PROTO_INIT) after proto->open()
succeeds, ensuring hu->priv is initialized before any work can be
scheduled.

Weakness: CWE-476 (NULL Pointer Dereference), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-23146?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23146?

Apply the vendor's patch.

## Is CVE-2026-23146 being exploited?

There is no known exploitation of CVE-2026-23146 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-2026-23146 and fix it if it is affected.

What it is: CVE-2026-23146 is a medium-severity vulnerability in Linux kernel, published on 14 Feb 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-2026-23146 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-2026-23146/ (Markdown: https://insights.sbomify.com/CVE-2026-23146/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23146
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23146
- OSV: https://osv.dev/vulnerability/CVE-2026-23146

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23146/
Summaries are generated and may contain mistakes; the official description above is the record.