# CVE-2025-21659: netdev: prevent accessing NAPI instances from another namespace

> Attackers can access NAPI instances from another network namespace, bypassing isolation and potentially reading sensitive data.

- **Severity:** High 8.1 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:L/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jan 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-21659, DEBIAN-CVE-2025-21659, GHSA-mg35-fw68-x22w, UBUNTU-CVE-2025-21659

## What is CVE-2025-21659?

CVE-2025-21659 is a high-severity missing authorization vulnerability in Linux kernel, published on 21 Jan 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:

netdev: prevent accessing NAPI instances from another namespace

The NAPI IDs were not fully exposed to user space prior to the netlink
API, so they were never namespaced. The netlink API must ensure that
at the very least NAPI instance belongs to the same netns as the owner
of the genl sock.

napi_by_id() can become static now, but it needs to move because of
dev_get_by_napi_id().

## Which versions are affected by CVE-2025-21659?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21659?

Apply the vendor's patch.

## Is CVE-2025-21659 being exploited?

There is no known exploitation of CVE-2025-21659 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-2025-21659 and fix it if it is affected.

What it is: CVE-2025-21659 is a high-severity missing authorization vulnerability in Linux kernel, published on 21 Jan 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-2025-21659 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-2025-21659/ (Markdown: https://insights.sbomify.com/CVE-2025-21659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21659
- OSV: https://osv.dev/vulnerability/CVE-2025-21659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21659/
Summaries are generated and may contain mistakes; the official description above is the record.