# CVE-2026-80923: xhci: dbgtty: Fix unregister on tty_register_driver() failure

> A use-after-free vulnerability in the Linux kernel xhci driver allows local attackers to cause a denial of service or potentially execute code during module unload.

- **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:** 9 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99954, BELL-CVE-2026-80923, DEBIAN-CVE-2026-80923, GHSA-m8fv-jwwg-rhrm, UBUNTU-CVE-2026-80923

## What is CVE-2026-80923?

CVE-2026-80923 is an use after free vulnerability in Linux, published on 9 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:

xhci: dbgtty: Fix unregister on tty_register_driver() failure

If tty_register_driver() fails, it drops the reference, but fails to set
the global dbc_tty_driver to NULL, causing the unregister to be called
again when module exits.

On module unload dbc_tty_exit() only gates its cleanup on the driver
pointer being non-NULL, so it operates on the already-freed driver:

    module_init(xhci_hcd_init)
      xhci_hcd_init()
        xhci_dbc_init()                       [return value ignored]
          dbc_tty_init()
            tty_register_driver() fails
              tty_driver_kref_put()           -> driver freed
              (dbc_tty_driver left dangling)
    ...
    module_exit(xhci_hcd_fini)
      xhci_hcd_fini()
        xhci_dbc_exit()
          dbc_tty_exit()
            if (dbc_tty_driver)               -> true (dangling)
              tty_unregister_driver()         -> use-after-free

## Which versions are affected by CVE-2026-80923?


## How do I fix CVE-2026-80923?

Apply the vendor's patch.

## Is CVE-2026-80923 being exploited?

There is no known exploitation of CVE-2026-80923 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80923 and fix it if it is affected.

What it is: CVE-2026-80923 is an use after free vulnerability in Linux, published on 9 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-2026-80923 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-2026-80923/ (Markdown: https://insights.sbomify.com/CVE-2026-80923/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80923
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80923
- OSV: https://osv.dev/vulnerability/CVE-2026-80923

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80923/
Summaries are generated and may contain mistakes; the official description above is the record.