CVE-2026-43438: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Remove redundant css_put() in scx_cgroup_init() The iterator css_for_each_descendant_pre() walks the cgroup hierarchy under cgroup_lock(). It does not increment the reference counts on yielded css structs. According to the cgroup documentation, css_put() should only be used to release a reference obtained via css_get() or css_tryget_online(). Since the iterator does not use either of these to acquire a reference, calling css_put() in the error path of scx_cgroup_init() causes a refcount underflow. Remove the unbalanced css_put() to prevent a potential Use-After-Free (UAF) vulnerability.

Affected products

• Linux Linux Kernel: from 6.12, before 6.12.78 (fixed in 6.12.78); from 6.13, before 6.18.19 (fixed in 6.18.19); from 6.19, before 6.19.9 (fixed in 6.19.9); version 7.0 only

Published 2026-05-08. Last modified 2026-06-17.