# CVE-2026-98742: ALSA: seq: Serialize compat port-info ioctls

> A race condition in the Linux kernel ALSA sequencer allows local attackers to trigger use-after-free, potentially leading to privilege escalation or 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:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-109013, BELL-CVE-2026-98742, DEBIAN-CVE-2026-98742, GHSA-qq2g-8h6m-jjjf, UBUNTU-CVE-2026-98742

## What is CVE-2026-98742?

CVE-2026-98742 is a vulnerability in Linux, published on 18 Oct 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: seq: Serialize compat port-info ioctls

The native sequencer ioctl path serializes handler calls with
client->ioctl_mutex, but the translated port-info compat path invokes the
same handlers through snd_seq_kernel_client_ctl() without taking that
mutex.

This lets concurrent compat CREATE_PORT requests pass the port-count
check before any request reaches the serialized insertion. The computed
integer port index can then exceed the address field range and wrap to an
existing index. Subsequent subscriber teardown can resolve the duplicate
address to the wrong port and access a freed subscriber.

Take ioctl_mutex while dispatching converted port-info requests, matching
the native ioctl path. All translated port-info commands share this
helper, so their accesses to the client port state are serialized as
well.

## Which versions are affected by CVE-2026-98742?


## How do I fix CVE-2026-98742?

Apply the vendor's patch.

## Is CVE-2026-98742 being exploited?

There is no known exploitation of CVE-2026-98742 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98742 and fix it if it is affected.

What it is: CVE-2026-98742 is a vulnerability in Linux, published on 18 Oct 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-2026-98742 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-2026-98742/ (Markdown: https://insights.sbomify.com/CVE-2026-98742/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98742
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98742
- OSV: https://osv.dev/vulnerability/CVE-2026-98742

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98742/
Summaries are generated and may contain mistakes; the official description above is the record.