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Vulnerability record · CVE-2026-43438 · published 8 May 2026

CVE-2026-43438: Linux kernel use after free vulnerability

Linux · Linux Kernel

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.

7.8 CVSS 3.1 High EPSS 0.17% · top 94.3% CWE-416 · Use after free
7.8CVSS 3.1 base score
0.17%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/1336b579f6079fb8520be03624fcd9ba443c930b Patch
https://git.kernel.org/stable/c/6eaaa67d6998f6c30c462b140db8c062e07ec473 Patch
https://git.kernel.org/stable/c/bf50f3285eda8a0173625fcdb5f183f96e1008cd Patch
https://git.kernel.org/stable/c/cc095cd305fddbe25a968e4a78436ff9476cf0f6 Patch

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Source: NIST National Vulnerability Database (record CVE-2026-43438), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.