# CVE-2026-97480: tty: serial: 8250: protect against NULL uart->port.dev in register

> A NULL pointer dereference in the Linux kernel 8250 serial driver can cause a system crash when registering ports without a parent device.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-103814, BELL-CVE-2026-97480, DEBIAN-CVE-2026-97480, GHSA-jrxp-w58r-g8c9, UBUNTU-CVE-2026-97480

## What is CVE-2026-97480?

CVE-2026-97480 is a vulnerability in Linux, published on 24 Sep 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:

tty: serial: 8250: protect against NULL uart->port.dev in register

serial8250_register_8250_port() conditionally copies uart->port.dev
from up->port.dev only when up->port.dev is non-NULL:

	if (up->port.dev) {
		uart->port.dev = up->port.dev;
		...
	}

So if both the existing uart slot and up have a NULL ->dev,
uart->port.dev remains NULL. The very next ACPI companion check
then dereferences it unconditionally:

	if (!has_acpi_companion(uart->port.dev)) {

has_acpi_companion() reads dev->fwnode without a NULL guard
(include/linux/acpi.h), so this NULL-derefs the kernel for the
remaining no-dev case rather than just skipping the
mctrl_gpio_init() initialisation as intended.

smatch flags the inconsistency:

  drivers/tty/serial/8250/8250_core.c:767
  serial8250_register_8250_port() error: 'uart->port.dev' could be
  null (see line 719)

Guard the call with a NULL check so register continues to work
for callers that legitimately have no parent device (legacy
non-OF/non-ACPI registrations).

No functional change for callers that pass a non-NULL ->dev.

## Which versions are affected by CVE-2026-97480?


## How do I fix CVE-2026-97480?

Apply the vendor's patch.

## Is CVE-2026-97480 being exploited?

There is no known exploitation of CVE-2026-97480 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97480 and fix it if it is affected.

What it is: CVE-2026-97480 is a vulnerability in Linux, published on 24 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-97480 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-97480/ (Markdown: https://insights.sbomify.com/CVE-2026-97480/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97480
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97480
- OSV: https://osv.dev/vulnerability/CVE-2026-97480

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97480/
Summaries are generated and may contain mistakes; the official description above is the record.