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.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98294 being exploited?
There is no known exploitation of CVE-2026-98294 in the wild and no public exploit code.
Sources
Also known as AZL-106038, BELL-CVE-2026-98294, DEBIAN-CVE-2026-98294, GHSA-5mg2-55jh-rjgr, UBUNTU-CVE-2026-98294.