CVE-2026-43438
sched_ext: Remove redundant css_put() in scx_cgroup_init()
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.
INFO
Published Date :
May 8, 2026, 3:16 p.m.
Last Modified :
May 21, 2026, 5:28 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Remove the unbalanced css_put() call.
- Ensure css_put() is only used for valid references.
- Apply kernel updates addressing this issue.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-43438.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-43438 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-43438
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-43438 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-43438 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
May. 21, 2026
Action Type Old Value New Value Added CWE CWE-416 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.12 up to (excluding) 6.12.78 *cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.19 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 6.19.9 Added Reference Type kernel.org: https://git.kernel.org/stable/c/1336b579f6079fb8520be03624fcd9ba443c930b Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/6eaaa67d6998f6c30c462b140db8c062e07ec473 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/bf50f3285eda8a0173625fcdb5f183f96e1008cd Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/cc095cd305fddbe25a968e4a78436ff9476cf0f6 Types: Patch -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 11, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 08, 2026
Action Type Old Value New Value Added 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. Added Reference https://git.kernel.org/stable/c/1336b579f6079fb8520be03624fcd9ba443c930b Added Reference https://git.kernel.org/stable/c/6eaaa67d6998f6c30c462b140db8c062e07ec473 Added Reference https://git.kernel.org/stable/c/bf50f3285eda8a0173625fcdb5f183f96e1008cd Added Reference https://git.kernel.org/stable/c/cc095cd305fddbe25a968e4a78436ff9476cf0f6