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

Q: Is CVE-2026-97925 being exploited?

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

Not scored Published 25 Sep 2026 Updated 19 Oct 2026

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

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

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?