# CVE-2026-93084: firmware: arm_scmi: Drop handle on protocol bind failures

> A use-after-free vulnerability in the Linux kernel SCMI driver allows local attackers to cause denial of service or potentially execute code via race conditions during protocol binding failures.

- **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:** 19 Oct 2026
- **Also known as:** AZL-102044, BELL-CVE-2026-93084, DEBIAN-CVE-2026-93084, GHSA-mw9p-h9xr-r672, UBUNTU-CVE-2026-93084

## What is CVE-2026-93084?

CVE-2026-93084 is an use after free 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: Drop handle on protocol bind failures

The SCMI bus notifier acquires an SCMI handle when the driver core emits
BUS_NOTIFY_BIND_DRIVER, before invoking the protocol driver probe
callback. The protocol probe path only checks whether sdev->handle is
set.

If device_link_add() fails after the handle has been acquired, the
protocol device can still bind with a valid handle but without the
dependency link to the SCMI parent. A concurrent parent unbind can then
miss the child and tear down the SCMI instance while the child still
holds a handle into it.

If the protocol driver probe later fails, for example with
-EPROBE_DEFER, the driver core emits BUS_NOTIFY_DRIVER_NOT_BOUND rather
than BUS_NOTIFY_UNBOUND_DRIVER. The SCMI notifier only released the
handle on BUS_NOTIFY_UNBOUND_DRIVER, so each failed protocol-device bind
leaked the SCMI instance users refcount and left sdev->handle set after
the failed probe.

Make the link helper report failure and drop the acquired handle if the
link cannot be created. Also handle BUS_NOTIFY_DRIVER_NOT_BOUND in the
same cleanup path used for unbind so failed probes balance the earlier
BUS_NOTIFY_BIND_DRIVER acquisition.

## Which versions are affected by CVE-2026-93084?


## How do I fix CVE-2026-93084?

Apply the vendor's patch.

## Is CVE-2026-93084 being exploited?

There is no known exploitation of CVE-2026-93084 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93084 and fix it if it is affected.

What it is: CVE-2026-93084 is an use after free 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-2026-93084 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-2026-93084/ (Markdown: https://insights.sbomify.com/CVE-2026-93084/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93084
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93084
- OSV: https://osv.dev/vulnerability/CVE-2026-93084

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93084/
Summaries are generated and may contain mistakes; the official description above is the record.