# CVE-2026-89891: media: em28xx: fix use-after-free of dev_next->devlist on disconnect

> A use-after-free in the em28xx media driver allows local attackers to cause kernel crashes or potentially execute code via USB device disconnection.

- **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:** 19 Oct 2026
- **Also known as:** AZL-101504, BELL-CVE-2026-89891, DEBIAN-CVE-2026-89891, GHSA-5cx6-377w-hc5f, UBUNTU-CVE-2026-89891

## What is CVE-2026-89891?

CVE-2026-89891 is an 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:

media: em28xx: fix use-after-free of dev_next->devlist on disconnect

When a device with has_dual_ts=1 is probed and the is_audio_only path
is taken, both dev and dev->dev_next are added to the global
em28xx_devlist via em28xx_init_extension(). However, during disconnect,
em28xx_close_extension(dev) only calls list_del(&dev->devlist), leaving
dev->dev_next->devlist still linked in the global list. When dev_next is
subsequently freed via kref_put(), its devlist entry becomes a dangling
pointer in em28xx_devlist. The next device probe that calls
em28xx_init_extension() triggers a list corruption BUG when list_add_tail
detects the freed node.

This bug was exposed by commit a368ecde8a50 ("USB: core: Fix duplicate
endpoint bug by clearing reserved bits in the descriptor") which clears
reserved bits in bEndpointAddress during endpoint parsing. This causes
fuzzed endpoint addresses like 0xf3 to be normalized to 0x83, which
em28xx interprets as a vendor audio endpoint, enabling the
is_audio_only + has_dual_ts code path that was previously unreachable
with such descriptors.

Fix this by removing dev->dev_next->devlist from the global list in
em28xx_close_extension() before the device is freed.

## Which versions are affected by CVE-2026-89891?


## How do I fix CVE-2026-89891?

Apply the vendor's patch.

## Is CVE-2026-89891 being exploited?

There is no known exploitation of CVE-2026-89891 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89891 and fix it if it is affected.

What it is: CVE-2026-89891 is an 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-2026-89891 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-2026-89891/ (Markdown: https://insights.sbomify.com/CVE-2026-89891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89891
- OSV: https://osv.dev/vulnerability/CVE-2026-89891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89891/
Summaries are generated and may contain mistakes; the official description above is the record.