# CVE-2026-89983: i2c: core: fix debugfs UAF on adapter removal

> A race condition in the Linux kernel i2c core allows a local attacker to trigger a use-after-free, potentially causing a system crash or arbitrary code execution.

- **Severity:** Not scored
- **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:** 19 Oct 2026
- **Also known as:** AZL-101520, BELL-CVE-2026-89983, DEBIAN-CVE-2026-89983, GHSA-xr2v-8c9q-cqgw, UBUNTU-CVE-2026-89983

## What is CVE-2026-89983?

CVE-2026-89983 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:

i2c: core: fix debugfs UAF on adapter removal

i2c_del_adapter() frees the adapter's debugfs directory before it
unregisters the adapter device, but the new_device sysfs attribute
stays writable until device_del(). A write racing with removal still
reaches i2c_device_probe(), which passes the freed adap->debugfs to
debugfs_create_dir() as the new client's parent:

  BUG: KASAN: slab-use-after-free in lookup_noperm_common+0x407/0x430
  Read of size 4 at addr ffff88803ef87810 by task syz.0.61/6090
   lookup_noperm_common+0x407/0x430
   simple_start_creating+0x9c/0x110
   debugfs_start_creating+0xdb/0x1a0
   debugfs_create_dir+0x24/0x350
   i2c_device_probe+0x814/0xbf0

It's technically possible to create a client after i2c_deregister_clients
has run. That client will never be unregistered and make
wait_for_completion hang.

Close the window by removing the new_device attribute at the start of
i2c_del_adapter(). device_remove_file() will drain any clients left.

## Which versions are affected by CVE-2026-89983?


## How do I fix CVE-2026-89983?

Apply the vendor's patch.

## Is CVE-2026-89983 being exploited?

There is no known exploitation of CVE-2026-89983 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89983 and fix it if it is affected.

What it is: CVE-2026-89983 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-2026-89983 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-2026-89983/ (Markdown: https://insights.sbomify.com/CVE-2026-89983/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89983
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89983
- OSV: https://osv.dev/vulnerability/CVE-2026-89983

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89983/
Summaries are generated and may contain mistakes; the official description above is the record.