# CVE-2026-68139: net/mlx5e: Use sender devcom for MPV master-up

> A race condition in the mlx5 driver causes a kernel NULL pointer dereference and system crash during PCIe error recovery.

- **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:** 10 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-68139, DEBIAN-CVE-2026-68139, GHSA-6jxm-mj96-cq7j, UBUNTU-CVE-2026-68139

## What is CVE-2026-68139?

CVE-2026-68139 is a vulnerability in Linux, published on 10 Aug 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:

net/mlx5e: Use sender devcom for MPV master-up

After PCIe DPC recovery, mlx5 reloads the affected functions and
replays multiport affiliation events. In the reported failure, the
first relevant device error was:

  pcieport 0000:10:01.1: DPC: containment event
  pcieport 0000:10:01.1: PCIe Bus Error: severity=Uncorrected (Fatal)
  pcieport 0000:10:01.1:    [ 5] SDES                   (First)

mlx5 recovered the PCI functions and resumed 0000:11:00.1. During
that resume, RDMA multiport binding replayed
MLX5_DRIVER_EVENT_AFFILIATION_DONE and mlx5e sent
MPV_DEVCOM_MASTER_UP. The host then panicked with:

  BUG: kernel NULL pointer dereference, address: 0000000000000010
  RIP: mlx5_devcom_comp_set_ready+0x5/0x40 [mlx5_core]
  RDI: 0000000000000000

Call trace included:

  mlx5_devcom_comp_set_ready
  mlx5e_devcom_event_mpv
  mlx5_devcom_send_event
  mlx5_ib_bind_slave_port
  mlx5r_mp_probe
  mlx5_pci_resume

MPV devcom registration publishes mlx5e private data to the component
peer list before mlx5e_devcom_init_mpv() stores the returned component
device in priv->devcom. A concurrent master-up event can therefore
reach a peer whose private data is visible but whose priv->devcom
backpointer is still NULL.

MPV_DEVCOM_MASTER_UP already carries the sender/master mlx5e private
data as event_data. The ready bit is stored on the shared devcom
component, not on an individual peer. Use the sender devcom when
marking the MPV component ready.

This preserves the readiness transition while avoiding a NULL
dereference of the peer devcom pointer during affiliation replay after
PCI error recovery.

## Which versions are affected by CVE-2026-68139?


## How do I fix CVE-2026-68139?

Apply the vendor's patch.

## Is CVE-2026-68139 being exploited?

There is no known exploitation of CVE-2026-68139 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68139 and fix it if it is affected.

What it is: CVE-2026-68139 is a vulnerability in Linux, published on 10 Aug 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-2026-68139 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-2026-68139/ (Markdown: https://insights.sbomify.com/CVE-2026-68139/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68139
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68139
- OSV: https://osv.dev/vulnerability/CVE-2026-68139

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68139/
Summaries are generated and may contain mistakes; the official description above is the record.