# CVE-2026-90044: usb: gadget: f_fs: Fix Use-After-Free in AIO error path

> A use-after-free vulnerability in the Linux kernel USB gadget functionfs driver allows attackers to potentially execute code or escalate privileges via a race condition in AIO error handling.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 16 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101273, BELL-CVE-2026-90044, DEBIAN-CVE-2026-90044, GHSA-xqqx-xhmm-5h73, UBUNTU-CVE-2026-90044

## What is CVE-2026-90044?

CVE-2026-90044 is a high-severity use after free 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_fs: Fix Use-After-Free in AIO error path

In ffs_epfile_write_iter() and ffs_epfile_read_iter(), when ffs_epfile_io()
fails with an error other than -EIOCBQUEUED, the io_data structure (`p`) is
freed. However, for AIO operations, the kiocb cancel function was already
armed and kiocb->private was set to `p`.

If a concurrent cancel operation (such as sys_io_cancel()) executes after
ffs_epfile_io() fails but before the function frees `p`, a Use-After-Free
can occur when the cancellation handler accesses the freed pointer.

To securely fix this race condition, we must properly un-arm the
cancellation. Invoking `kiocb->ki_complete()` does exactly this by
acquiring `ctx->ctx_lock` and safely removing the kiocb from the active
sequence. In doing so, it ensures that a parallel io_cancel can no longer
discover the kiocb, effectively closing the race window.

We then return -EIOCBQUEUED to notify the VFS layer that the kiocb has been
consumed and it should avoid attempting to complete the request again or
triggering subsequent completion handlers.

## Which versions are affected by CVE-2026-90044?


## How do I fix CVE-2026-90044?

Apply the vendor's patch.

## Is CVE-2026-90044 being exploited?

There is no known exploitation of CVE-2026-90044 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90044 and fix it if it is affected.

What it is: CVE-2026-90044 is a high-severity use after free 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-2026-90044 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-2026-90044/ (Markdown: https://insights.sbomify.com/CVE-2026-90044/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90044
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90044
- OSV: https://osv.dev/vulnerability/CVE-2026-90044

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90044/
Summaries are generated and may contain mistakes; the official description above is the record.