CVE-2023-53176 serial: 8250: Reinit port->pm on port specific driver unbind
A use-after-free in the Linux kernel serial driver causes a system crash when unbinding specific hardware drivers, leading to denial of service.
- 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
What is CVE-2023-53176?
CVE-2023-53176 is a high-severity use after free vulnerability in Linux kernel, published on 15 Sep 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:
serial: 8250: Reinit port->pm on port specific driver unbind
When we unbind a serial port hardware specific 8250 driver, the generic serial8250 driver takes over the port. After that we see an oops about 10 seconds later. This can produce the following at least on some TI SoCs:
Unhandled fault: imprecise external abort (0x1406) Internal error: : 1406 [#1] SMP ARM
Turns out that we may still have the serial port hardware specific driver port->pm in use, and serial8250_pm() tries to call it after the port specific driver is gone:
serial8250_pm [8250_base] from uart_change_pm+0x54/0x8c [serial_base] uart_change_pm [serial_base] from uart_hangup+0x154/0x198 [serial_base] uart_hangup [serial_base] from __tty_hangup.part.0+0x328/0x37c __tty_hangup.part.0 from disassociate_ctty+0x154/0x20c disassociate_ctty from do_exit+0x744/0xaac do_exit from do_group_exit+0x40/0x8c do_group_exit from __wake_up_parent+0x0/0x1c
Let's fix the issue by calling serial8250_set_defaults() in serial8250_unregister_port(). This will set the port back to using the serial8250 default functions, and sets the port->pm to point to serial8250_pm.
Which versions are affected by CVE-2023-53176?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53176?
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-2023-53176 being exploited?
There is no known exploitation of CVE-2023-53176 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53176, DEBIAN-CVE-2023-53176, GHSA-j67r-mf5q-82pc, UBUNTU-CVE-2023-53176.