# CVE-2026-89979: ALSA: pcm: Fix race between non-atomic ops and trigger-start

> A race condition in the Linux kernel ALSA PCM subsystem allows concurrent operations to cause state inconsistencies and potential system warnings or crashes.

- **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:** AZL-101397, BELL-CVE-2026-89979, DEBIAN-CVE-2026-89979, GHSA-r2rw-736q-8cv3, UBUNTU-CVE-2026-89979

## What is CVE-2026-89979?

CVE-2026-89979 is a high-severity 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:

ALSA: pcm: Fix race between non-atomic ops and trigger-start

We protect the races of the concurrent state transitions between
atomic PCM ops, but the checks between the non-atomic ops (hw_params,
hw_free and prepare) and the atomic ops aren't perfect; there is a
check of the conflicting PCM state at the beginning of hw_params & co,
but the atomic PCM ops can be still issued during the non-atomic PCM
operations.  An example such scenario is that a thread A re-issues the
PREPARE or HW_PARAMS for the already prepared stream, while another
thread B triggers the PCM start in the middle of the prepare
operation.  Although this usually doesn't lead to much serious issues,
it can give some inconsistency as reported by syzkaller (such as
ODEBUG warning).

There are various atomic PCM ops, and basically the only problem is
the PCM start as it operates from the PREPARED state.  Other trigger
commands (stop, etc) are for the running or the other special state,
hence they are filtered as pre-condition.

This patch is for preventing the PCM trigger-start during the non-
atomic operations in order to address the problems above.
Fortunately, the hw_params, hw_free and prepare operations call
snd_pcm_buffer_access_lock(), and this can be used for checking the
concurrent operations at the PCM trigger -- which sets the
runtime->buffer_accessing to a negative (if possible), so the PCM
trigger just needs to check the runtime->buffer_accessing value; if
it's negative, it means the concurrent non-atomic PCM ops is running.

## Which versions are affected by CVE-2026-89979?


## How do I fix CVE-2026-89979?

Apply the vendor's patch.

## Is CVE-2026-89979 being exploited?

There is no known exploitation of CVE-2026-89979 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89979 and fix it if it is affected.

What it is: CVE-2026-89979 is a high-severity 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-2026-89979 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-2026-89979/ (Markdown: https://insights.sbomify.com/CVE-2026-89979/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89979
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89979
- OSV: https://osv.dev/vulnerability/CVE-2026-89979

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89979/
Summaries are generated and may contain mistakes; the official description above is the record.