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Linux KernelOperating system · Linux

CVE-2026-53328

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-01
Fix available
A fix is available. Upgrade to 6.12.94 / 6.18.36 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available 7 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A false WARN triggers in sched_ext's scx_cgroup_move_task() when systemd's user manager modifies subtree_control while a sched_ext scheduler is loaded. The root cause is a mismatch: scx_cgroup_can_attach() arms cgrp_moving_from based on cgroup identity, but migration operates on css identity, leading to NULL cgrp_moving_from in legitimate css-only migrations.

MitigationThis is a kernel bug fix requiring a code change to remove the false warning; no user-facing mitigation applies beyond kernel patching.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.12, < 6.12.94>= 6.13, < 6.18.36>= 6.19, < 7.0.13= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed kernel version
    Run `uname -r` or `cat /proc/version` to get the running kernel version
    Affected if version falls within any of these ranges: >= 6.12 and < 6.12.94, >= 6.13 and < 6.18.36, >= 6.19 and < 7.0.13, or equals 7.1
  2. Determine if sched_ext (scx) is enabled
    Check if the scx kernel module is loaded (`lsmod | grep scx`) or verify CONFIG_SCHED_EXT=y in kernel config (`cat /boot/config-$(uname -r) | grep SCHED_EXT`)
    Affected if sched_ext is compiled into the kernel or loaded as a module
  3. Search kernel logs for the false positive WARNING
    Run `dmesg | grep -i 'scx_cgroup_move_task'` or check journalctl for messages containing 'WARNING' and 'scx_cgroup_move_task' or 'cgrp_moving_from'
    Affected if WARNING messages mentioning scx_cgroup_move_task and NULL cgrp_moving_from appear in kernel logs, particularly when systemd user manager is active

You are affected if your kernel version is within the affected ranges AND sched_ext is enabled AND you observe the false positive WARNING in logs during normal systemd user manager operations.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.12.94 / 6.18.36 / 7.0.13 or later
Fixed in 6.12.946.18.367.0.13
Vendor patch git.kernel.org →
Interim mitigation

This is a kernel bug fix requiring a code change to remove the false warning; no user-facing mitigation applies beyond kernel patching.

Recommended fix High confidence

6.12.94 (also fixed in 6.18.36, 7.0.13 and later)

  1. The fix removes an erroneous WARN_ON() in scx_cgroup_move_task() that triggers on legitimate css-only migrations where cgrp_moving_from is NULL but the migration is still valid.
  2. In file kernel/sched/ext.c, locate the WARN_ON() call near line 3227 in function scx_cgroup_move_task() and remove it or comment it out.
  3. Alternatively, the upstream commits (referenced in git.kernel.org) contain the fix which removes the warning condition entirely since the NULL check already guards the function.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53328 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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