CVE-2026-93220 sched_ext: Keep kick_sync waiting on the rq's own CPU
A race condition in the Linux kernel's sched_ext scheduler can cause a deadlock, leading to denial of service.
- 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-2026-93220?
CVE-2026-93220 is a vulnerability in Linux, published on 24 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:
sched_ext: Keep kick_sync waiting on the rq's own CPU
kick_sync_wait_bal_cb() assumes it runs on the rq's CPU from the __schedule() tail: the snapshots it compares against live in that CPU's percpu area and the busy-wait runs with the rq lock dropped and IRQs enabled.
However, dispatch can now drop the rq lock while the callback sits queued, and rq lock takers in that window (the sched class change paths, the scx task iterator) flush pending balance callbacks on release, running the callback on a foreign CPU. Such a run compares against unrelated snapshots and can deadlock when the executing CPU is itself a wait target.
Bail on a foreign CPU and leave the wait state alone. The wait only observes progress that the resched kicks already guarantee and the rq's next wait picks up the stale cpus_to_sync bits.
Which versions are affected by CVE-2026-93220?
How do I fix CVE-2026-93220?
Apply the vendor's patch.
Is CVE-2026-93220 being exploited?
There is no known exploitation of CVE-2026-93220 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-93220, GHSA-mp4r-853f-vhwr, UBUNTU-CVE-2026-93220.