# CVE-2026-98753: tty: tty_port: restore TTY_IO_ERROR on activation failure

> A race condition in the Linux kernel TTY subsystem can cause a kernel panic via NULL pointer dereference when accessing powered-down ports.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-109020, BELL-CVE-2026-98753, DEBIAN-CVE-2026-98753, GHSA-fxvh-5c26-7p3q, UBUNTU-CVE-2026-98753

## What is CVE-2026-98753?

CVE-2026-98753 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:

tty: tty_port: restore TTY_IO_ERROR on activation failure

Make sure to restore the TTY_IO_ERROR flag if activation fails to
prevent I/O attempts on a port that is gone or powered down.

This specifically avoids issues like kernel panic due to unclocked
accesses or NULL-pointer dereferences when accessing powered down or
deregistered ports when a TTY ioctl races with hangup and open.

Note that the flag is set again in tty_port_close() but not restoring it
on activation failure leaves a window where drivers fail to handle the
ioctl-hangup race.

## Which versions are affected by CVE-2026-98753?


## How do I fix CVE-2026-98753?

Apply the vendor's patch.

## Is CVE-2026-98753 being exploited?

There is no known exploitation of CVE-2026-98753 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98753 and fix it if it is affected.

What it is: CVE-2026-98753 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-2026-98753 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-2026-98753/ (Markdown: https://insights.sbomify.com/CVE-2026-98753/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98753
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98753
- OSV: https://osv.dev/vulnerability/CVE-2026-98753

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98753/
Summaries are generated and may contain mistakes; the official description above is the record.