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

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 include Linux kernel.

How do I fix CVE-2025-21659?

Apply the vendor's patch.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

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 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-21659, DEBIAN-CVE-2025-21659, GHSA-mg35-fw68-x22w, UBUNTU-CVE-2025-21659.