# CVE-2026-98294: Bluetooth: hci_qca: Do not write to the serial port after it is closed

> A use-after-free vulnerability in the Linux kernel Bluetooth driver allows local attackers to cause a denial of service or potentially execute code by triggering a specific driver unbind sequence.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **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-106038, BELL-CVE-2026-98294, DEBIAN-CVE-2026-98294, GHSA-5mg2-55jh-rjgr, UBUNTU-CVE-2026-98294

## What is CVE-2026-98294?

CVE-2026-98294 is an 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:

Bluetooth: hci_qca: Do not write to the serial port after it is closed

hci_uart_close() closes the serdev port if HCI_QUIRK_NON_PERSISTENT_SETUP
is set (for example, for the WCN399x family). A failed hci_dev_open_sync()
following a successful qca_setup() calls hdev->close() but not
hdev->shutdown(), so the port is closed while power->vregs_on is left true.
qca_serdev_remove() then passes its power->vregs_on test and calls
qca_power_off(), which writes to the closed port unconditionally.

Seen on a WCN3988 by unbinding the driver after a controller failure. The
trace below is from a 7.0.0 based kernel, where qca_power_off() was still
named qca_power_shutdown():

  Unable to handle kernel NULL pointer dereference at virtual address
  0000000000000038
  Call trace:
   tty_set_termios+0x50/0x238 (P)
   ttyport_set_baudrate+0x84/0xc0
   serdev_device_set_baudrate+0x24/0x40
   qca_power_shutdown+0x158/0x1fc [hci_uart]
   qca_serdev_remove+0x54/0x68 [hci_uart]
   serdev_drv_remove+0x1c/0x2c
   device_remove+0x4c/0x80
   device_release_driver_internal+0x1cc/0x224
   device_driver_detach+0x18/0x24
   unbind_store+0xb4/0xc0

Check HCI_UART_PROTO_READY, which hci_uart_close() clears in the same place
it closes the port, before writing to it. The regulator disable is left
unconditional so the controller is still powered down.

The dangling serport->tty that turns this into a use-after-free is
addressed in a separate patch.

## Which versions are affected by CVE-2026-98294?


## How do I fix CVE-2026-98294?

Apply the vendor's patch.

## Is CVE-2026-98294 being exploited?

There is no known exploitation of CVE-2026-98294 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98294 and fix it if it is affected.

What it is: CVE-2026-98294 is an 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-2026-98294 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-2026-98294/ (Markdown: https://insights.sbomify.com/CVE-2026-98294/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98294
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98294
- OSV: https://osv.dev/vulnerability/CVE-2026-98294

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98294/
Summaries are generated and may contain mistakes; the official description above is the record.