# CVE-2026-31736: net: ethernet: mtk_ppe: avoid NULL deref when gmac0 is disabled

> A NULL pointer dereference in the MediaTek PPE driver causes a system crash when gmac0 is disabled, requiring a kernel patch.

- **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:** 1 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-31736, DEBIAN-CVE-2026-31736, GHSA-pp62-pwj6-ppp4, UBUNTU-CVE-2026-31736

## What is CVE-2026-31736?

CVE-2026-31736 is a medium-severity vulnerability in Linux kernel, published on 1 May 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: ethernet: mtk_ppe: avoid NULL deref when gmac0 is disabled

If the gmac0 is disabled, the precheck for a valid ingress device will
cause a NULL pointer deref and crash the system. This happens because
eth->netdev[0] will be NULL but the code will directly try to access
netdev_ops.

Instead of just checking for the first net_device, it must be checked if
any of the mtk_eth net_devices is matching the netdev_ops of the ingress
device.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31736?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31736?

Apply the vendor's patch.

## Is CVE-2026-31736 being exploited?

There is no known exploitation of CVE-2026-31736 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-2026-31736 and fix it if it is affected.

What it is: CVE-2026-31736 is a medium-severity vulnerability in Linux kernel, published on 1 May 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-2026-31736 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-2026-31736/ (Markdown: https://insights.sbomify.com/CVE-2026-31736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31736
- OSV: https://osv.dev/vulnerability/CVE-2026-31736

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31736/
Summaries are generated and may contain mistakes; the official description above is the record.