# CVE-2026-68409: wifi: mac80211: defer link RX stats percpu free to RCU

> A race condition in Linux kernel Wi-Fi MLO link removal allows use-after-free of percpu stats, potentially leading to code execution or crashes.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-95042, BELL-CVE-2026-68409, DEBIAN-CVE-2026-68409, GHSA-g5f7-qj4q-4w5v, UBUNTU-CVE-2026-68409

## What is CVE-2026-68409?

CVE-2026-68409 is a high-severity use after free vulnerability in Linux, published on 10 Aug 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:

wifi: mac80211: defer link RX stats percpu free to RCU

sta_remove_link() frees a removed MLO link's RX stats percpu buffer right
away, but defers only the link container to RCU:

	sta_info_free_link(&alloc->info);
	kfree_rcu(alloc, rcu_head);

The RX fast path reads link_sta under rcu_read_lock and writes the percpu
stats. A reader that resolved link_sta before the removal keeps the
pointer. The container stays alive from the kfree_rcu, so the read still
works. But the percpu block it points to is already freed. This needs
uses_rss. That is when pcpu_rx_stats exists.

The full STA teardown frees the deflink stats only after
synchronize_net(). The link removal path had no such barrier. The race is
hard to win in practice, but the free should still wait for RCU.

Free the link together with its data from a single RCU callback, so the
percpu block is reclaimed only after readers drain.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-68409?


## How do I fix CVE-2026-68409?

Apply the vendor's patch.

## Is CVE-2026-68409 being exploited?

There is no known exploitation of CVE-2026-68409 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68409 and fix it if it is affected.

What it is: CVE-2026-68409 is a high-severity use after free vulnerability in Linux, published on 10 Aug 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-2026-68409 in the wild and no public exploit code.

Affected product: Linux. 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-2026-68409/ (Markdown: https://insights.sbomify.com/CVE-2026-68409/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68409
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68409
- OSV: https://osv.dev/vulnerability/CVE-2026-68409

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68409/
Summaries are generated and may contain mistakes; the official description above is the record.