# CVE-2026-97925: tick/broadcast: Plug clockevents replacement race

> A race condition in the Linux kernel tick broadcast subsystem can cause a system crash when a clock event device is replaced.

- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104648, BELL-CVE-2026-97925, DEBIAN-CVE-2026-97925, GHSA-frpq-r7pw-xq84, UBUNTU-CVE-2026-97925

## What is CVE-2026-97925?

CVE-2026-97925 is a vulnerability in Linux, published on 25 Sep 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:

tick/broadcast: Plug clockevents replacement race

朱恺乾 reported and decoded the following race condition when a broadcast
device is replaced:

CPUA					CPUB
 __tick_broadcast_oneshot_control()
   bc = tick_broadcast_device.evtdev;
					tick_install_broadcast_device(dev)
        				clockevents_exchange_device(cur, dev)
					   shutdown(cur);
					   detach(cur);
					   cur->handler = noop;
					   tick_broadcast_device.evtdev = dev;

  tick_broadcast_set_event(bc, next_event); <- FAIL: arms a detached device.

If the original broadcast device has a restricted interrupt affinity mask
and the last CPU in that mask goes offline then the BUG() in
tick_cleanup_dead_cpu() triggers because the clockevent device is not in
detached state.

The reason for this is that tick_install_broadcast_device() is not
serialized vs. tick broadcast operations.

The obvious cure is to serialize tick_install_broadcast_device() with
tick_broadcast_lock against a concurrent tick broadcast operation.

That requires to split clockevents_exchange_device() into two parts, one
which does the exchange, shutdown and detach operation and the other which
drops the module reference count. This is required because the module
reference cannot be dropped while holding tick_broadcast_lock.

Let clockevents_exchange_device() do both operations as before, but let the
broadcast device code take the two step approach and do the device
exchange under tick_broadcast_lock and drop the module reference count
after releasing it.

## Which versions are affected by CVE-2026-97925?


## How do I fix CVE-2026-97925?

Apply the vendor's patch.

## Is CVE-2026-97925 being exploited?

There is no known exploitation of CVE-2026-97925 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97925 and fix it if it is affected.

What it is: CVE-2026-97925 is a vulnerability in Linux, published on 25 Sep 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-2026-97925 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-2026-97925/ (Markdown: https://insights.sbomify.com/CVE-2026-97925/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97925
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97925
- OSV: https://osv.dev/vulnerability/CVE-2026-97925

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97925/
Summaries are generated and may contain mistakes; the official description above is the record.