# CVE-2025-39947: net/mlx5e: Harden uplink netdev access against device unbind

> A missing null check in the Linux kernel mlx5e driver allows a local attacker to trigger a kernel panic via device unbind, causing denial of service.

- **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:** 4 Oct 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-68181, AZL-75342, BELL-CVE-2025-39947, DEBIAN-CVE-2025-39947, GHSA-r3wm-5qjq-c8qp, ROOT-OS-DEBIAN-12-CVE-2025-39947, ROOT-OS-DEBIAN-13-CVE-2025-39947, ROOT-OS-UBUNTU-2204-CVE-2025-39947, ROOT-OS-UBUNTU-2404-CVE-2025-39947, UBUNTU-CVE-2025-39947

## What is CVE-2025-39947?

CVE-2025-39947 is a medium-severity vulnerability in Linux kernel, published on 4 Oct 2025. 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: Harden uplink netdev access against device unbind

The function mlx5_uplink_netdev_get() gets the uplink netdevice
pointer from mdev->mlx5e_res.uplink_netdev. However, the netdevice can
be removed and its pointer cleared when unbound from the mlx5_core.eth
driver. This results in a NULL pointer, causing a kernel panic.

 BUG: unable to handle page fault for address: 0000000000001300
 at RIP: 0010:mlx5e_vport_rep_load+0x22a/0x270 [mlx5_core]
 Call Trace:
  <TASK>
  mlx5_esw_offloads_rep_load+0x68/0xe0 [mlx5_core]
  esw_offloads_enable+0x593/0x910 [mlx5_core]
  mlx5_eswitch_enable_locked+0x341/0x420 [mlx5_core]
  mlx5_devlink_eswitch_mode_set+0x17e/0x3a0 [mlx5_core]
  devlink_nl_eswitch_set_doit+0x60/0xd0
  genl_family_rcv_msg_doit+0xe0/0x130
  genl_rcv_msg+0x183/0x290
  netlink_rcv_skb+0x4b/0xf0
  genl_rcv+0x24/0x40
  netlink_unicast+0x255/0x380
  netlink_sendmsg+0x1f3/0x420
  __sock_sendmsg+0x38/0x60
  __sys_sendto+0x119/0x180
  do_syscall_64+0x53/0x1d0
  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Ensure the pointer is valid before use by checking it for NULL. If it
is valid, immediately call netdev_hold() to take a reference, and
preventing the netdevice from being freed while it is in use.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-39947?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39947?

Apply the vendor's patch.

## Is CVE-2025-39947 being exploited?

There is no known exploitation of CVE-2025-39947 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-2025-39947 and fix it if it is affected.

What it is: CVE-2025-39947 is a medium-severity vulnerability in Linux kernel, published on 4 Oct 2025. 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-2025-39947 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-2025-39947/ (Markdown: https://insights.sbomify.com/CVE-2025-39947/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39947
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39947
- OSV: https://osv.dev/vulnerability/CVE-2025-39947

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39947/
Summaries are generated and may contain mistakes; the official description above is the record.