# CVE-2026-93093: firmware: arm_scmi: Publish channel state before callbacks

> A race condition in the Linux kernel SCMI driver allows a NULL pointer dereference, leading to a system crash or denial of service.

- **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:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-110444, BELL-CVE-2026-93093, DEBIAN-CVE-2026-93093, GHSA-wj2w-288c-r9m4, UBUNTU-CVE-2026-93093

## What is CVE-2026-93093?

CVE-2026-93093 is a vulnerability in Linux, published on 17 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:

firmware: arm_scmi: Publish channel state before callbacks

Transport setup can enable callbacks before the setup routine returns.
mailbox_chan_setup() registers the mailbox client with
mbox_request_channel(), and the mailbox controller startup path can enable
interrupt delivery before SCMI mailbox channel state has been published.
Similarly, smc_chan_setup() requests the optional A2P completion IRQ before
the SMC transport has made its cinfo pointer visible.

If a pending or spurious callback fires in those windows, the transport RX
callback can dereference a NULL transport cinfo pointer. Publishing only
the transport-private pointer is not sufficient either: an early callback
can enter the SCMI core before scmi_chan_setup() has assigned
cinfo->handle.
The core derives scmi_info from cinfo->handle in the RX path, so a NULL
handle can still fault even when the transport-private cinfo is valid.

Assign cinfo->handle before invoking the transport setup callback. Publish
the mailbox and SMC transport-private channel state before requesting the
mailbox channels or IRQ, and clear the early-published pointers again on
setup failure. Also unwind mailbox setup devres resources on failure so an
optional RX setup error that is ignored by the core does not leave stale
transport state behind.

## Which versions are affected by CVE-2026-93093?


## How do I fix CVE-2026-93093?

Apply the vendor's patch.

## Is CVE-2026-93093 being exploited?

There is no known exploitation of CVE-2026-93093 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93093 and fix it if it is affected.

What it is: CVE-2026-93093 is a vulnerability in Linux, published on 17 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-2026-93093 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-2026-93093/ (Markdown: https://insights.sbomify.com/CVE-2026-93093/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93093
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93093
- OSV: https://osv.dev/vulnerability/CVE-2026-93093

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93093/
Summaries are generated and may contain mistakes; the official description above is the record.