# CVE-2026-31579: wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit

> A race condition in the Linux kernel WireGuard module causes a hung task and denial of service during network namespace cleanup.

- **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:** 24 Apr 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-83828, BELL-CVE-2026-31579, DEBIAN-CVE-2026-31579, GHSA-h53c-6597-vmfw, ROOT-OS-DEBIAN-11-CVE-2026-31579, ROOT-OS-DEBIAN-12-CVE-2026-31579, ROOT-OS-DEBIAN-13-CVE-2026-31579, ROOT-OS-UBUNTU-2204-CVE-2026-31579, ROOT-OS-UBUNTU-2404-CVE-2026-31579, UBUNTU-CVE-2026-31579

## What is CVE-2026-31579?

CVE-2026-31579 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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:

wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit

wg_netns_pre_exit() manually acquires rtnl_lock() inside the
pernet .pre_exit callback.  This causes a hung task when another
thread holds rtnl_mutex - the cleanup_net workqueue (or the
setup_net failure rollback path) blocks indefinitely in
wg_netns_pre_exit() waiting to acquire the lock.

Convert to .exit_rtnl, introduced in commit 7a60d91c690b ("net:
Add ->exit_rtnl() hook to struct pernet_operations."), where the
framework already holds RTNL and batches all callbacks under a
single rtnl_lock()/rtnl_unlock() pair, eliminating the contention
window.

The rcu_assign_pointer(wg->creating_net, NULL) is safe to move
from .pre_exit to .exit_rtnl (which runs after synchronize_rcu())
because all RCU readers of creating_net either use maybe_get_net()
- which returns NULL for a dying namespace with zero refcount - or
access net->user_ns which remains valid throughout the entire
ops_undo_list sequence.

[ Jason: added __net_exit and __read_mostly annotations that were missing. ]

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31579?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31579?

Apply the vendor's patch.

## Is CVE-2026-31579 being exploited?

There is no known exploitation of CVE-2026-31579 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-2026-31579 and fix it if it is affected.

What it is: CVE-2026-31579 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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-2026-31579 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-2026-31579/ (Markdown: https://insights.sbomify.com/CVE-2026-31579/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31579
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31579
- OSV: https://osv.dev/vulnerability/CVE-2026-31579

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31579/
Summaries are generated and may contain mistakes; the official description above is the record.