CVE-2026-43438 is a high-severity vulnerability in the Linux kernel's sched_ext subsystem involving an unbalanced reference count operation. The issue arises from a redundant call to css_put() in the scx_cgroup_init() function, which leads to a reference count underflow and a potential Use-After-Free (UAF) condition. This occurs because the iterator css_for_each_descendant_pre() does not increment reference counts on the css structs it yields, yet css_put() is called as if it should release a reference. Removing this redundant css_put() call prevents the UAF vulnerability.