# CVE-2025-21676: net: fec: handle page_pool_dev_alloc_pages error

> A null pointer dereference in the Linux kernel FEC network driver can cause a system crash when memory allocation fails under pressure.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Jan 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-56387, BELL-CVE-2025-21676, DEBIAN-CVE-2025-21676, GHSA-2cvp-cxm8-hg6v, ROOT-OS-DEBIAN-12-CVE-2025-21676, UBUNTU-CVE-2025-21676

## What is CVE-2025-21676?

CVE-2025-21676 is a high-severity vulnerability in Linux kernel, published on 31 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: fec: handle page_pool_dev_alloc_pages error

The fec_enet_update_cbd function calls page_pool_dev_alloc_pages but did
not handle the case when it returned NULL. There was a WARN_ON(!new_page)
but it would still proceed to use the NULL pointer and then crash.

This case does seem somewhat rare but when the system is under memory
pressure it can happen. One case where I can duplicate this with some
frequency is when writing over a smbd share to a SATA HDD attached to an
imx6q.

Setting /proc/sys/vm/min_free_kbytes to higher values also seems to solve
the problem for my test case. But it still seems wrong that the fec driver
ignores the memory allocation error and can crash.

This commit handles the allocation error by dropping the current packet.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-21676?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21676?

Apply the vendor's patch.

## Is CVE-2025-21676 being exploited?

There is no known exploitation of CVE-2025-21676 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-2025-21676 and fix it if it is affected.

What it is: CVE-2025-21676 is a high-severity vulnerability in Linux kernel, published on 31 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-21676 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-2025-21676/ (Markdown: https://insights.sbomify.com/CVE-2025-21676/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21676
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21676
- OSV: https://osv.dev/vulnerability/CVE-2025-21676

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21676/
Summaries are generated and may contain mistakes; the official description above is the record.