CVE-2026-46154 sched_ext: Read scx_root under scx_cgroup_ops_rwsem in cgroup setters
A use-after-free in the Linux kernel scheduler allows attackers to execute arbitrary code or escalate privileges if sched_ext is enabled.
- 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-2026-46154?
CVE-2026-46154 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 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: Read scx_root under scx_cgroup_ops_rwsem in cgroup setters
scx_group_set_{weight,idle,bandwidth}() cache scx_root before acquiring scx_cgroup_ops_rwsem, so the pointer can be stale by the time the op runs. If the loaded scheduler is disabled and freed (via RCU work) and another is enabled between the naked load and the rwsem acquire, the reader sees scx_cgroup_enabled=true (the new scheduler's) but dereferences the freed one - UAF on SCX_HAS_OP(sch, ...) / SCX_CALL_OP(sch, ...).
scx_cgroup_enabled is toggled only under scx_cgroup_ops_rwsem write (scx_cgroup_{init,exit}), so reading scx_root inside the rwsem read section correlates @sch with the enabled snapshot.
Weakness: CWE-416
Which versions are affected by CVE-2026-46154?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46154?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-46154 being exploited?
There is no known exploitation of CVE-2026-46154 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-46154, DEBIAN-CVE-2026-46154, GHSA-xcff-q6mv-v46w, UBUNTU-CVE-2026-46154.