Description
In the Linux kernel, the following vulnerability has been resolved:

cgroup: split cgroup_destroy_wq into 3 workqueues

A hung task can occur during [1] LTP cgroup testing when repeatedly
mounting/unmounting perf_event and net_prio controllers with
systemd.unified_cgroup_hierarchy=1. The hang manifests in
cgroup_lock_and_drain_offline() during root destruction.

Related case:
cgroup_fj_function_perf_event cgroup_fj_function.sh perf_event
cgroup_fj_function_net_prio cgroup_fj_function.sh net_prio

Call Trace:
cgroup_lock_and_drain_offline+0x14c/0x1e8
cgroup_destroy_root+0x3c/0x2c0
css_free_rwork_fn+0x248/0x338
process_one_work+0x16c/0x3b8
worker_thread+0x22c/0x3b0
kthread+0xec/0x100
ret_from_fork+0x10/0x20

Root Cause:

CPU0 CPU1
mount perf_event umount net_prio
cgroup1_get_tree cgroup_kill_sb
rebind_subsystems // root destruction enqueues
// cgroup_destroy_wq
// kill all perf_event css
// one perf_event css A is dying
// css A offline enqueues cgroup_destroy_wq
// root destruction will be executed first
css_free_rwork_fn
cgroup_destroy_root
cgroup_lock_and_drain_offline
// some perf descendants are dying
// cgroup_destroy_wq max_active = 1
// waiting for css A to die

Problem scenario:
1. CPU0 mounts perf_event (rebind_subsystems)
2. CPU1 unmounts net_prio (cgroup_kill_sb), queuing root destruction work
3. A dying perf_event CSS gets queued for offline after root destruction
4. Root destruction waits for offline completion, but offline work is
blocked behind root destruction in cgroup_destroy_wq (max_active=1)

Solution:
Split cgroup_destroy_wq into three dedicated workqueues:
cgroup_offline_wq – Handles CSS offline operations
cgroup_release_wq – Manages resource release
cgroup_free_wq – Performs final memory deallocation

This separation eliminates blocking in the CSS free path while waiting for
offline operations to complete.

[1] https://github.com/linux-test-project/ltp/blob/master/runtest/controllers
Published: 2025-10-04
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4379-1 linux-6.1 security update
Debian DLA Debian DLA DLA-4404-1 linux security update
Debian DSA Debian DSA DSA-6053-1 linux security update
EUVD EUVD EUVD-2025-32380 In the Linux kernel, the following vulnerability has been resolved: cgroup: split cgroup_destroy_wq into 3 workqueues A hung task can occur during [1] LTP cgroup testing when repeatedly mounting/unmounting perf_event and net_prio controllers with systemd.unified_cgroup_hierarchy=1. The hang manifests in cgroup_lock_and_drain_offline() during root destruction. Related case: cgroup_fj_function_perf_event cgroup_fj_function.sh perf_event cgroup_fj_function_net_prio cgroup_fj_function.sh net_prio Call Trace: cgroup_lock_and_drain_offline+0x14c/0x1e8 cgroup_destroy_root+0x3c/0x2c0 css_free_rwork_fn+0x248/0x338 process_one_work+0x16c/0x3b8 worker_thread+0x22c/0x3b0 kthread+0xec/0x100 ret_from_fork+0x10/0x20 Root Cause: CPU0 CPU1 mount perf_event umount net_prio cgroup1_get_tree cgroup_kill_sb rebind_subsystems // root destruction enqueues // cgroup_destroy_wq // kill all perf_event css // one perf_event css A is dying // css A offline enqueues cgroup_destroy_wq // root destruction will be executed first css_free_rwork_fn cgroup_destroy_root cgroup_lock_and_drain_offline // some perf descendants are dying // cgroup_destroy_wq max_active = 1 // waiting for css A to die Problem scenario: 1. CPU0 mounts perf_event (rebind_subsystems) 2. CPU1 unmounts net_prio (cgroup_kill_sb), queuing root destruction work 3. A dying perf_event CSS gets queued for offline after root destruction 4. Root destruction waits for offline completion, but offline work is blocked behind root destruction in cgroup_destroy_wq (max_active=1) Solution: Split cgroup_destroy_wq into three dedicated workqueues: cgroup_offline_wq – Handles CSS offline operations cgroup_release_wq – Manages resource release cgroup_free_wq – Performs final memory deallocation This separation eliminates blocking in the CSS free path while waiting for offline operations to complete. [1] https://github.com/linux-test-project/ltp/blob/master/runtest/controllers
Ubuntu USN Ubuntu USN USN-8033-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-3 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8034-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-4 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-5 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8034-2 Linux kernel (NVIDIA Tegra IGX) vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-6 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-7 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8033-8 Linux kernel (Intel IoTG) vulnerabilities
Ubuntu USN Ubuntu USN USN-8095-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8095-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8100-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8095-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-8095-4 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8125-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8126-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8095-5 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8141-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8163-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8165-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8163-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8243-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8261-1 Linux kernel (Xilinx) vulnerabilities
History

Fri, 23 Jan 2026 20:15:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*

Mon, 06 Oct 2025 22:45:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low


Mon, 06 Oct 2025 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Sat, 04 Oct 2025 07:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: cgroup: split cgroup_destroy_wq into 3 workqueues A hung task can occur during [1] LTP cgroup testing when repeatedly mounting/unmounting perf_event and net_prio controllers with systemd.unified_cgroup_hierarchy=1. The hang manifests in cgroup_lock_and_drain_offline() during root destruction. Related case: cgroup_fj_function_perf_event cgroup_fj_function.sh perf_event cgroup_fj_function_net_prio cgroup_fj_function.sh net_prio Call Trace: cgroup_lock_and_drain_offline+0x14c/0x1e8 cgroup_destroy_root+0x3c/0x2c0 css_free_rwork_fn+0x248/0x338 process_one_work+0x16c/0x3b8 worker_thread+0x22c/0x3b0 kthread+0xec/0x100 ret_from_fork+0x10/0x20 Root Cause: CPU0 CPU1 mount perf_event umount net_prio cgroup1_get_tree cgroup_kill_sb rebind_subsystems // root destruction enqueues // cgroup_destroy_wq // kill all perf_event css // one perf_event css A is dying // css A offline enqueues cgroup_destroy_wq // root destruction will be executed first css_free_rwork_fn cgroup_destroy_root cgroup_lock_and_drain_offline // some perf descendants are dying // cgroup_destroy_wq max_active = 1 // waiting for css A to die Problem scenario: 1. CPU0 mounts perf_event (rebind_subsystems) 2. CPU1 unmounts net_prio (cgroup_kill_sb), queuing root destruction work 3. A dying perf_event CSS gets queued for offline after root destruction 4. Root destruction waits for offline completion, but offline work is blocked behind root destruction in cgroup_destroy_wq (max_active=1) Solution: Split cgroup_destroy_wq into three dedicated workqueues: cgroup_offline_wq – Handles CSS offline operations cgroup_release_wq – Manages resource release cgroup_free_wq – Performs final memory deallocation This separation eliminates blocking in the CSS free path while waiting for offline operations to complete. [1] https://github.com/linux-test-project/ltp/blob/master/runtest/controllers
Title cgroup: split cgroup_destroy_wq into 3 workqueues
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T21:39:37.071Z

Reserved: 2025-04-16T07:20:57.149Z

Link: CVE-2025-39953

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2025-10-04T08:15:48.627

Modified: 2026-01-23T20:01:35.360

Link: CVE-2025-39953

cve-icon Redhat

Severity : Low

Publid Date: 2025-10-04T00:00:00Z

Links: CVE-2025-39953 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-06T14:41:53Z

Weaknesses