CVE-2026-98883: serial: 8250_port: recognize UPIO_AU

Published Oct 23, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved:

serial: 8250port: recognize UPIOAU

My MIPS Alchemy systems generate the following warning during probe of the 8250 driver:

WARNING: drivers/tty/serial/8250/8250port.c:462 at setiofromupio+0xfc/0x124, CPU#0: swapper/0/1 Unsupported UART type 4 [...] [<80521d40>] setiofromupio+0xfc/0x124 [<80521dfc>] serial8250setdefaults+0x94/0xe0 [<80520fb4>] serial8250register8250port+0x288/0x51c [<805214ec>] serial8250probe+0x160/0x1e8 [<8053b5f0>] platformprobe+0x64/0x90

The least invasive fix is to recognize UPIOAU (type 4) in setiofromupio() and do nothing, since all parameters have already been set up in 8250rt288x.c::auplatformsetup().

Run-tested on Alchemy Au1300 platform.

Affected Software

1 affected component

Linux Linux kernel

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Compensating control
Modify set_io_from_upio() to recognize UPIO_AU (type 4) and do nothing, since all parameters have already been set up during the 8250 driver probe.

Event History

Oct 23, 2026

CVE Published

via MITRE·11:37 AM

Data Sourced

via MITRE·11:37 AM

Description

Frequently Asked Questions

Which systems are affected by this issue?

The issue is reported on MIPS Alchemy systems using the 8250 serial driver, and it was run-tested on an Alchemy Au1300 platform. The affected UART type is UPIO_AU (type 4).

When does the problem occur?

It occurs during probing and registration of the 8250 serial driver, when set_io_from_upio() encounters the UPIO_AU UART type and emits an unsupported-UART warning.

Is a configuration change required to mitigate the issue?

The provided information describes a code fix rather than a configuration workaround. The fix makes set_io_from_upio() recognize UPIO_AU and take no action because its parameters are already configured by au_platform_setup().

How can administrators identify an affected system?

Check kernel logs during 8250 driver probe for a warning from drivers/tty/serial/8250/8250_port.c in set_io_from_upio() stating "Unsupported UART type 4."

CVE-2026-98883: serial: 8250_port: recognize UPIO_AU

Affected Software

Remediation

Event History

Frequently Asked Questions

Which systems are affected by this issue?

When does the problem occur?

Is a configuration change required to mitigate the issue?

How can administrators identify an affected system?

Company

Resources

Contact

Frequently Asked Questions

Which systems are affected by this issue?

When does the problem occur?

Is a configuration change required to mitigate the issue?

How can administrators identify an affected system?