# CVE-2026-68411: wifi: mac80211_hwsim: clamp virtio RX length before skb_put

> A malicious virtio backend can cause a guest kernel panic by reporting an oversized RX length, leading to denial of service.

- **Severity:** Not scored
- **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:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-68411, DEBIAN-CVE-2026-68411, GHSA-wpwp-37fg-5mf6, UBUNTU-CVE-2026-68411

## What is CVE-2026-68411?

CVE-2026-68411 is a denial of service 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_hwsim: clamp virtio RX length before skb_put

hwsim_virtio_rx_work() passes the virtqueue used-ring length reported by
the device straight to skb_put() on a fixed-size receive skb. A backend
reporting a length larger than the skb tailroom drives skb_put() past the
buffer end and hits skb_over_panic() -- a host-triggerable guest panic
(denial of service).

Clamp the length to the skb's available room before skb_put(). A
conforming device never reports more than the posted buffer size, so valid
frames are unaffected; a truncated over-report then fails the
length/header checks in hwsim_virtio_handle_cmd() and is dropped, so
truncating rather than dropping here cannot be turned into a parsing
problem.

## Which versions are affected by CVE-2026-68411?


## How do I fix CVE-2026-68411?

Apply the vendor's patch.

## Is CVE-2026-68411 being exploited?

There is no known exploitation of CVE-2026-68411 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68411 and fix it if it is affected.

What it is: CVE-2026-68411 is a denial of service 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-2026-68411 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-2026-68411/ (Markdown: https://insights.sbomify.com/CVE-2026-68411/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68411
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68411
- OSV: https://osv.dev/vulnerability/CVE-2026-68411

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68411/
Summaries are generated and may contain mistakes; the official description above is the record.