# CVE-2026-31756: usb: dwc2: gadget: Fix spin_lock/unlock mismatch in dwc2_hsotg_udc_stop()

> A locking mismatch in the Linux kernel's dwc2 USB gadget driver can cause a deadlock, leading to a 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 May 2026
- **Updated:** 23 May 2026
- **Also known as:** BELL-CVE-2026-31756, DEBIAN-CVE-2026-31756, GHSA-r5fx-27qq-pwqg, ROOT-OS-UBUNTU-2204-CVE-2026-31756, ROOT-OS-UBUNTU-2404-CVE-2026-31756, UBUNTU-CVE-2026-31756

## What is CVE-2026-31756?

CVE-2026-31756 is a medium-severity vulnerability in Linux kernel, published on 1 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:

usb: dwc2: gadget: Fix spin_lock/unlock mismatch in dwc2_hsotg_udc_stop()

dwc2_gadget_exit_clock_gating() internally calls call_gadget() macro,
which expects hsotg->lock to be held since it does spin_unlock/spin_lock
around the gadget driver callback invocation.

However, dwc2_hsotg_udc_stop() calls dwc2_gadget_exit_clock_gating()
without holding the lock. This leads to:
 - spin_unlock on a lock that is not held (undefined behavior)
 - The lock remaining held after dwc2_gadget_exit_clock_gating() returns,
   causing a deadlock when spin_lock_irqsave() is called later in the
   same function.

Fix this by acquiring hsotg->lock before calling
dwc2_gadget_exit_clock_gating() and releasing it afterwards, which
satisfies the locking requirement of the call_gadget() macro.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-31756?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31756?

Apply the vendor's patch.

## Is CVE-2026-31756 being exploited?

There is no known exploitation of CVE-2026-31756 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-2026-31756 and fix it if it is affected.

What it is: CVE-2026-31756 is a medium-severity vulnerability in Linux kernel, published on 1 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-2026-31756 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-2026-31756/ (Markdown: https://insights.sbomify.com/CVE-2026-31756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31756
- OSV: https://osv.dev/vulnerability/CVE-2026-31756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31756/
Summaries are generated and may contain mistakes; the official description above is the record.