# CVE-2021-47164: net/mlx5e: Fix null deref accessing lag dev

> A null pointer dereference in the Linux kernel's mlx5e driver can cause a system crash when processing network events.

- **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:** 25 Mar 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47164, GHSA-vf6v-52pq-2h8v, UBUNTU-CVE-2021-47164

## What is CVE-2021-47164?

CVE-2021-47164 is a medium-severity vulnerability in Linux kernel, published on 25 Mar 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:

net/mlx5e: Fix null deref accessing lag dev

It could be the lag dev is null so stop processing the event.
In bond_enslave() the active/backup slave being set before setting the
upper dev so first event is without an upper dev.
After setting the upper dev with bond_master_upper_dev_link() there is
a second event and in that event we have an upper dev.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-47164?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47164?

Apply the vendor's patch.

## Is CVE-2021-47164 being exploited?

There is no known exploitation of CVE-2021-47164 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-2021-47164 and fix it if it is affected.

What it is: CVE-2021-47164 is a medium-severity vulnerability in Linux kernel, published on 25 Mar 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-2021-47164 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-2021-47164/ (Markdown: https://insights.sbomify.com/CVE-2021-47164/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47164
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47164
- OSV: https://osv.dev/vulnerability/CVE-2021-47164

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47164/
Summaries are generated and may contain mistakes; the official description above is the record.