# CVE-2026-80659: mmc: vub300: defer reset until cmd_mutex is unlocked

> A recursive locking bug in the vub300 MMC driver causes a deadlock and system hang when a USB command times out, requiring local access to trigger.

- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80659, DEBIAN-CVE-2026-80659, GHSA-7xh8-9fpc-p64f, UBUNTU-CVE-2026-80659

## What is CVE-2026-80659?

CVE-2026-80659 is a vulnerability in Linux, published on 28 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:

mmc: vub300: defer reset until cmd_mutex is unlocked

vub300_cmndwork_thread() holds cmd_mutex while it sends a command and
waits for the command response.  If the response wait times out,
__vub300_command_response() kills the command URBs and then synchronously
resets the USB device through usb_reset_device().

That reset path re-enters the driver through vub300_pre_reset(), which
also takes cmd_mutex.  The worker therefore tries to acquire the same
mutex recursively while it is still holding it from the command path.

This issue was found by our static analysis tool and then manually
reviewed against the current tree.

The grounded PoC kept the real worker and timeout/reset carrier:

  vub300_cmndwork_thread()
  __vub300_command_response()
  usb_lock_device_for_reset()
  usb_reset_device()
  vub300_pre_reset()

Lockdep reported the same-task recursive acquisition on cmd_mutex:

  WARNING: possible recursive locking detected
  ... (&test_vub300.cmd_mutex) ... at: usb_reset_device... [vuln_msv]
  ... (&test_vub300.cmd_mutex) ... at: vub300_cmndwork_thread+0x12/0x20 [vuln_msv]
  Workqueue: vub300_cmd_wq vub300_cmndwork_thread [vuln_msv]
  *** DEADLOCK ***

Return a flag from __vub300_command_response() when the timeout path needs
a device reset, then perform the reset after vub300_cmndwork_thread() has
cleared the in-flight command state and dropped cmd_mutex.  The reset is
still attempted before mmc_request_done(), preserving the existing request
completion ordering while avoiding the recursive lock.

## Which versions are affected by CVE-2026-80659?


## How do I fix CVE-2026-80659?

Apply the vendor's patch.

## Is CVE-2026-80659 being exploited?

There is no known exploitation of CVE-2026-80659 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80659 and fix it if it is affected.

What it is: CVE-2026-80659 is a vulnerability in Linux, published on 28 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-2026-80659 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-2026-80659/ (Markdown: https://insights.sbomify.com/CVE-2026-80659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80659
- OSV: https://osv.dev/vulnerability/CVE-2026-80659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80659/
Summaries are generated and may contain mistakes; the official description above is the record.