---
cve: "CVE-2026-53328"
severity: "LOW"
cvss: 3.1
epss: "12%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-07-01 14:16:40"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-11T15:25:24+02:00"
---

# CVE-2026-53328

> 3.1 LOW

## Beschreibung

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

sched_ext: Don't warn on NULL cgrp_moving_from in scx_cgroup_move_task()

A WARN fires when systemd's user manager writes "+cpu +memory +pids" to
its own subtree_control while a sched_ext scheduler is loaded:

  WARNING: at kernel/sched/ext.c:3227 scx_cgroup_move_task+0xa8/0xb0
   scx_cgroup_move_task+0xa8/0xb0
   sched_move_task+0x134/0x290
   cpu_cgroup_attach+0x39/0x70
   cgroup_migrate_execute+0x37d/0x450
   cgroup_update_dfl_csses+0x1e3/0x270
   cgroup_subtree_control_write+0x3e7/0x440

scx_cgroup_can_attach() arms cgrp_moving_from only when a task's cpu
cgroup changes. It can still be NULL when scx_cgroup_move_task() runs,
through this sequence:

  Step                               Result
  ---------------------------------  ----------------------------------
  1. cpu enabled on cgroup G         cpu css = A
  2. cpu toggled off then on for G   A killed, B created (same cgroup)
  3. an exiting task keeps A alive   migration skips it, A now stale
  4. +memory migrates G              stale A vs current B pulls cpu in
  5. cpu attach runs for all tasks   hits a live, cpu-unchanged task
  6. scx_cgroup_move_task() on it    cgrp_moving_from NULL -> WARN

The mismatch is that scx_cgroup_can_attach() keys on cgroup identity
while migration drives the move on css identity, so a NULL cgrp_moving_from
here is a legitimate css-only migration, not a missing prep.

The call is already gated on cgrp_moving_from, so just drop the warning.
ops.cgroup_prep_move() and ops.cgroup_move() stay paired.

## Patch verfügbar (OSV)

- Kernel ≥ 6.12.94
- Kernel ≥ 6.18.36
- Kernel ≥ 7.0.13

## Referenzen

- <https://git.kernel.org/stable/c/cdff2eb97be147d2ce52ac1327841068781f25dc>
- <https://git.kernel.org/stable/c/0ffcad63b19a1cadb475c9f405a93607fdcd0d7c>
- <https://git.kernel.org/stable/c/bc75f5951fac4e49d175c4433fc08fb1ec01172f>
- <https://git.kernel.org/stable/c/02e545c4297a26dbbc41df81b831e7f605bcd306>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-53328) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_