---
id: "CVE-2026-98883"
kind: "vulnerability"
aliases: ["CVE-2026-98883"]
title: "Linux kernel: serial 8250 driver warns on MIPS Alchemy UART type"
severity: "unknown"
cvss: null
epss: 0.00198
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["linux-kernel", "mips-alchemy", "runtime"]
not_affected_if: ["non-mips-alchemy-hardware"]
published_at: "2026-10-23T12:18:21+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:51+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98883", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-98883", "first_seen_at": "2026-10-25T12:38:51+00:00"}]
---

# Linux kernel: serial 8250 driver warns on MIPS Alchemy UART type

The Linux kernel 8250 serial driver did not recognize the UPIO_AU port type used on MIPS Alchemy systems, so it printed a kernel warning during probe. The fix makes the driver accept that type and skip the step, which only affects boot logs on those boards.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98883
- 2026-10-25T12:38:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-98883

## From the sources

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

serial: 8250_port: recognize UPIO_AU

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

WARNING: drivers/tty/serial/8250/8250_port.c:462 at set_io_from_upio+0xfc/0x124, CPU#0: swapper/0/1
Unsupported UART type 4
[...]
[<80521d40>] set_io_from_upio+0xfc/0x124
[<80521dfc>] serial8250_set_defaults+0x94/0xe0
[<80520fb4>] serial8250_register_8250_port+0x288/0x51c
[<805214ec>] serial8250_probe+0x160/0x1e8
[<8053b5f0>] platform_probe+0x64/0x90

The least invasive fix is to recognize UPIO_AU (type 4) in set_io_from_upio()
and do nothing, since all parameters have already been set up in
8250_rt288x.c::au_platform_setup().

Run-tested on Alchemy Au1300 platform.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_