# CVE-2026-98693: thunderbolt: Hold a router reference for each allocated HopID

> A use-after-free vulnerability in the Linux kernel Thunderbolt driver allows local attackers to cause a denial of service by triggering a race condition during device unbinding.

- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98693, DEBIAN-CVE-2026-98693, GHSA-4h8h-x3h6-2f57, UBUNTU-CVE-2026-98693

## What is CVE-2026-98693?

CVE-2026-98693 is an use after free 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:

thunderbolt: Hold a router reference for each allocated HopID

tb_stop() drops the reference to all DP tunnels but does not deactivate
them, thus nothing cancels a dprx_work still in flight (which holds its
own tunnel reference) and the tunnel can outlive tb_switch_remove(). The
HopID releases in tb_path_free() then operate on freed IDAs and trigger
warnings like

  ida_free called for id=8 which is not allocated.

This can be triggered by unbinding the driver while a DP tunnel is still
waiting for the DPRX capabilities read to finish. On the Apple NHI
unplugging the cable runs into just that reliably because the read can
never finish right now and because the unplug powers down the entire
USB4 complex and removes the NHI device.

Take a router reference whenever an input or output HopID is allocated
and drop it again after the HopID is released. This keeps the ports and
their HopID IDAs alive for as long as they are used.

The KUnit tests allocate routers without ever registering their devices
so initialize the embedded struct device there as well and drop its
initial reference when the test is finished.

## Which versions are affected by CVE-2026-98693?


## How do I fix CVE-2026-98693?

Apply the vendor's patch.

## Is CVE-2026-98693 being exploited?

There is no known exploitation of CVE-2026-98693 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98693 and fix it if it is affected.

What it is: CVE-2026-98693 is an use after free 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-2026-98693 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-2026-98693/ (Markdown: https://insights.sbomify.com/CVE-2026-98693/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98693
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98693
- OSV: https://osv.dev/vulnerability/CVE-2026-98693

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98693/
Summaries are generated and may contain mistakes; the official description above is the record.