# CVE-2026-98747: serial: core: fix NULL pointer dereference in serial_core_unregister_port()

> A local attacker with high privileges can trigger a NULL pointer dereference in the Linux kernel serial core, causing a system crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109137, BELL-CVE-2026-98747, DEBIAN-CVE-2026-98747, GHSA-6854-f26p-xx8r, UBUNTU-CVE-2026-98747

## What is CVE-2026-98747?

CVE-2026-98747 is a vulnerability in Linux, published on 18 Oct 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:

serial: core: fix NULL pointer dereference in serial_core_unregister_port()

port->port_dev is NULL when no port device is installed: it is cleared
on teardown, and never set if registration failed before
serial_core_port_device_add().  serial_core_unregister_port() passes it
straight to serial_core_get_ctrl_dev(), which dereferences it:

  KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
  RIP: serial_core_unregister_port
  Call Trace:
   serial8250_unregister_port
   serial8250_remove
   unbind_store

Return early when there is no port device, and read port->port_dev
under port_mutex.

Also clear port->port_dev on the serial_core_register_port() error
path, where the port device has already been removed.

## Which versions are affected by CVE-2026-98747?


## How do I fix CVE-2026-98747?

Apply the vendor's patch.

## Is CVE-2026-98747 being exploited?

There is no known exploitation of CVE-2026-98747 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98747 and fix it if it is affected.

What it is: CVE-2026-98747 is a vulnerability in Linux, published on 18 Oct 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-2026-98747 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-2026-98747/ (Markdown: https://insights.sbomify.com/CVE-2026-98747/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98747
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98747
- OSV: https://osv.dev/vulnerability/CVE-2026-98747

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98747/
Summaries are generated and may contain mistakes; the official description above is the record.