# CVE-2025-21917: usb: renesas_usbhs: Flush the notify_hotplug_work

> A null pointer dereference in the Renesas USBHS driver causes a kernel crash during continuous unbind/bind operations, leading to denial of service.

- **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:** 1 Apr 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-59925, AZL-59963, BELL-CVE-2025-21917, DEBIAN-CVE-2025-21917, GHSA-hf5w-7g55-wh36, ROOT-OS-UBUNTU-2404-CVE-2025-21917, UBUNTU-CVE-2025-21917

## What is CVE-2025-21917?

CVE-2025-21917 is a medium-severity vulnerability in Linux kernel, published on 1 Apr 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:

usb: renesas_usbhs: Flush the notify_hotplug_work

When performing continuous unbind/bind operations on the USB drivers
available on the Renesas RZ/G2L SoC, a kernel crash with the message
"Unable to handle kernel NULL pointer dereference at virtual address"
may occur. This issue points to the usbhsc_notify_hotplug() function.

Flush the delayed work to avoid its execution when driver resources are
unavailable.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-21917?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21917?

Apply the vendor's patch.

## Is CVE-2025-21917 being exploited?

There is no known exploitation of CVE-2025-21917 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-2025-21917 and fix it if it is affected.

What it is: CVE-2025-21917 is a medium-severity vulnerability in Linux kernel, published on 1 Apr 2025. 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-2025-21917 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-2025-21917/ (Markdown: https://insights.sbomify.com/CVE-2025-21917/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21917
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21917
- OSV: https://osv.dev/vulnerability/CVE-2025-21917

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21917/
Summaries are generated and may contain mistakes; the official description above is the record.