# CVE-2021-46994: can: mcp251x: fix resume from sleep before interface was brought up

> A null pointer dereference in the Linux kernel MCP251x CAN driver causes a system crash when resuming from sleep before the interface is enabled.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 28 Feb 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-46994, GHSA-9h3w-jq64-m799, UBUNTU-CVE-2021-46994

## What is CVE-2021-46994?

CVE-2021-46994 is a medium-severity vulnerability in Linux kernel, published on 28 Feb 2024. 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:

can: mcp251x: fix resume from sleep before interface was brought up

Since 8ce8c0abcba3 the driver queues work via priv->restart_work when
resuming after suspend, even when the interface was not previously
enabled. This causes a null dereference error as the workqueue is only
allocated and initialized in mcp251x_open().

To fix this we move the workqueue init to mcp251x_can_probe() as there
is no reason to do it later and repeat it whenever mcp251x_open() is
called.

[mkl: fix error handling in mcp251x_stop()]

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-46994?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-46994?

Apply the vendor's patch.

## Is CVE-2021-46994 being exploited?

There is no known exploitation of CVE-2021-46994 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-46994 and fix it if it is affected.

What it is: CVE-2021-46994 is a medium-severity vulnerability in Linux kernel, published on 28 Feb 2024. 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-2021-46994 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2021-46994/ (Markdown: https://insights.sbomify.com/CVE-2021-46994/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-46994
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-46994
- OSV: https://osv.dev/vulnerability/CVE-2021-46994

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-46994/
Summaries are generated and may contain mistakes; the official description above is the record.