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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-14 · updated 2026-10-19
Weakness: CWE-476

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.

Affected products

Linux kernel: from 5.4.293 before 5.5; from 5.10.237 before 5.10.249; from 5.15.181 before 5.15.199; from 6.1.135 before 6.1.162; from 6.6.88 before 6.6.123; from 6.12.24 before 6.12.69 — fixed in 5.10.249, 5.15.199, 5.5, 6.1.162, 6.12.69, 6.14

How to fix

Upgrade to a fixed version: Linux kernel 5.10.249, 5.15.199, 5.5, 6.1.162. Check the vendor advisory for mitigations.

References

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