CVE-2026-74593 sched_ext: Take cgroup_lock() first in scx_cgroup_lock()
A race condition in the Linux kernel's sched_ext subsystem can cause a deadlock, leading to denial of service when specific cgroup operations are performed concurrently.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74593?
CVE-2026-74593 is a vulnerability in Linux, published on 22 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:
sched_ext: Take cgroup_lock() first in scx_cgroup_lock()
scx_cgroup_lock() write-locks scx_cgroup_ops_rwsem and then takes cgroup_lock(), which can deadlock through kernfs:
scx enable/disable cgroup rmdir cpu.weight write ------------------ ------------ ---------------- cgroup_lock() percpu_down_write(rwsem) cgroup_lock() kernfs_get_active() percpu_down_read(rwsem) kernfs_drain()
The enable path waits for the rmdir to release cgroup_mutex. The rmdir, deactivating the cpu controller's files, waits in kernfs_drain() for the write's active reference. The write, in scx_group_set_weight(), waits for the rwsem behind the pending writer.
Take cgroup_lock() first. The set_* paths take no cgroup locks inside the read side, so a pending write-lock then only waits for read sections that always run to completion, and no dependency from the rwsem back to cgroup_mutex remains.
Which versions are affected by CVE-2026-74593?
How do I fix CVE-2026-74593?
Apply the vendor's patch.
Is CVE-2026-74593 being exploited?
There is no known exploitation of CVE-2026-74593 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74593, DEBIAN-CVE-2026-74593, GHSA-jp6g-jm55-gwj8, UBUNTU-CVE-2026-74593.