# CVE-2026-89942: iio: buffer: Fix potential use-after-free in anonymous buffer release

> A use-after-free in the Linux kernel IIO subsystem allows local attackers to execute arbitrary code or escalate privileges via anonymous buffer release.

- **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:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89942, DEBIAN-CVE-2026-89942, GHSA-3g64-jv43-3qjf, UBUNTU-CVE-2026-89942

## What is CVE-2026-89942?

CVE-2026-89942 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:

iio: buffer: Fix potential use-after-free in anonymous buffer release

An anonymous buffer handle holds a reference to the underlying IIO device.
The reference is dropped in the buffer handle's release function. If the
device has been removed, either through unbind or hot-unplug, the buffer
handle might hold the last reference.

The release function takes the mutex for the buffer using a guard, which
means the unlock happens after all the code in the function, including
`iio_device_put()`. If the anonymous buffer holds the last reference this
might free both the IIO device and the buffer, which contains the mutex,
leading to use-after-free when the mutex is unlocked.

Fix this by using a scoped guard just around the buffer dmabuf list access,
making sure the mutex is unlocked before releasing the IIO device.

Version 10 of the patch that introduced this issue used this exact scheme
of first unlocking and then dropping the reference [1]. During review it
was suggested to use a guard instead, and version 11 made that change [2].

## Which versions are affected by CVE-2026-89942?


## How do I fix CVE-2026-89942?

Apply the vendor's patch.

## Is CVE-2026-89942 being exploited?

There is no known exploitation of CVE-2026-89942 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89942 and fix it if it is affected.

What it is: CVE-2026-89942 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-2026-89942 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-2026-89942/ (Markdown: https://insights.sbomify.com/CVE-2026-89942/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89942
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89942
- OSV: https://osv.dev/vulnerability/CVE-2026-89942

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89942/
Summaries are generated and may contain mistakes; the official description above is the record.