# CVE-2026-90021: usb: gadget: f_midi: initialize work in f_midi_alloc()

> A missing initialization in the Linux kernel USB MIDI gadget driver can cause a null pointer dereference and system crash when the device is freed without being bound.

- **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:** 16 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101144, BELL-CVE-2026-90021, DEBIAN-CVE-2026-90021, GHSA-9v89-j77v-qgfm, UBUNTU-CVE-2026-90021

## What is CVE-2026-90021?

CVE-2026-90021 is a vulnerability in Linux, published on 16 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:

usb: gadget: f_midi: initialize work in f_midi_alloc()

f_midi_alloc initializes free_ref to 1 and it can only be incremented
when a sound card is registered via f_midi_register_card().
f_midi_register_card() is only called in f_midi_bind() which actually
performs INIT_WORK. If f_midi_bind() is never run, work is not
initialized and the if condition in f_midi_free becomes true,
this results in a warning later in __flush_work as work->func = 0.
Fix this by moving INIT_WORK from f_midi_bind() to f_midi_alloc().

## Which versions are affected by CVE-2026-90021?


## How do I fix CVE-2026-90021?

Apply the vendor's patch.

## Is CVE-2026-90021 being exploited?

There is no known exploitation of CVE-2026-90021 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90021 and fix it if it is affected.

What it is: CVE-2026-90021 is a vulnerability in Linux, published on 16 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-2026-90021 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-2026-90021/ (Markdown: https://insights.sbomify.com/CVE-2026-90021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90021
- OSV: https://osv.dev/vulnerability/CVE-2026-90021

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90021/
Summaries are generated and may contain mistakes; the official description above is the record.