# CVE-2026-43255: wifi: libertas: fix WARNING in usb_tx_block

> A race condition in the Libertas Wi-Fi driver allows triggering a kernel warning and potential denial of service by submitting USB requests concurrently.

- **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:** 6 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-43255, DEBIAN-CVE-2026-43255, GHSA-w929-9wq4-xrmp, ROOT-OS-DEBIAN-11-CVE-2026-43255, ROOT-OS-UBUNTU-2204-CVE-2026-43255, ROOT-OS-UBUNTU-2404-CVE-2026-43255, UBUNTU-CVE-2026-43255

## What is CVE-2026-43255?

CVE-2026-43255 is a medium-severity vulnerability in Linux kernel, published on 6 May 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: libertas: fix WARNING in usb_tx_block

The function usb_tx_block() submits cardp->tx_urb without ensuring that
any previous transmission on this URB has completed. If a second call
occurs while the URB is still active (e.g. during rapid firmware loading),
usb_submit_urb() detects the active state and triggers a warning:
'URB submitted while active'.

Fix this by enforcing serialization: call usb_kill_urb() before
submitting the new request. This ensures the URB is idle and safe to reuse.

## Which versions are affected by CVE-2026-43255?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43255?

Apply the vendor's patch.

## Is CVE-2026-43255 being exploited?

There is no known exploitation of CVE-2026-43255 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-2026-43255 and fix it if it is affected.

What it is: CVE-2026-43255 is a medium-severity vulnerability in Linux kernel, published on 6 May 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-2026-43255 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-2026-43255/ (Markdown: https://insights.sbomify.com/CVE-2026-43255/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43255
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43255
- OSV: https://osv.dev/vulnerability/CVE-2026-43255

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43255/
Summaries are generated and may contain mistakes; the official description above is the record.