# CVE-2026-74331: firmware_loader: Fix recursive lock in device_cache_fw_images()

> A recursive locking deadlock in the Linux kernel firmware loader can cause a system hang during suspend or hibernation when memory allocation fails.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74331, DEBIAN-CVE-2026-74331, GHSA-2whr-3329-9322, UBUNTU-CVE-2026-74331

## What is CVE-2026-74331?

CVE-2026-74331 is a denial of service vulnerability in Linux, published on 15 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:

firmware_loader: Fix recursive lock in device_cache_fw_images()

A recursive locking deadlock can occur in the firmware loader's power
management notification handler.

During system suspend or hibernation preparation, fw_pm_notify() calls
device_cache_fw_images(). This function acquires fw_lock to set the
firmware cache state to FW_LOADER_START_CACHE and then iterates over all
devices using dpm_for_each_dev() while still holding the lock.

For each device, dev_cache_fw_image() schedules asynchronous work to cache
the firmware. If memory allocation for the async work entry fails (e.g., in
out-of-memory conditions), async_schedule_node_domain() falls back to
executing the work function synchronously in the current thread.

The synchronous execution path (__async_dev_cache_fw_image() ->
cache_firmware() -> request_firmware() -> assign_fw()) attempts to acquire
fw_lock again. Since the current thread already holds fw_lock, this results
in a recursive locking deadlock.

Fix this by releasing fw_lock immediately after updating the cache state
and before calling dpm_for_each_dev(). The lock is only needed to protect
the state update. Concurrent firmware requests will correctly see the
FW_LOADER_START_CACHE state and use the piggyback mechanism, which is
independently protected by its own fwc->name_lock.

## Which versions are affected by CVE-2026-74331?


## How do I fix CVE-2026-74331?

Apply the vendor's patch.

## Is CVE-2026-74331 being exploited?

There is no known exploitation of CVE-2026-74331 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74331 and fix it if it is affected.

What it is: CVE-2026-74331 is a denial of service vulnerability in Linux, published on 15 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-2026-74331 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-2026-74331/ (Markdown: https://insights.sbomify.com/CVE-2026-74331/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74331
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74331
- OSV: https://osv.dev/vulnerability/CVE-2026-74331

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74331/
Summaries are generated and may contain mistakes; the official description above is the record.