* [CVE-2026-93150][MODERATE REGULAR] cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream
@ 2026-09-18 11:10 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-18 11:10 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93150
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream
Commit: e422b32e6a57269ca8164c60674a78bee85cf5fb
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e422b32e6a57269ca8164c60674a78bee85cf5fb
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150
Analysis date: Fri, 18 Sep 2026 07:10:01 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93150 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150
The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.
This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.
The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.
Published priority for this report: MODERATE REGULAR
Manual review required: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-93150 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93150 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H';CWE-362;CWE-667;CWE-682;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.3';DESCR 'A race in cgroup/cpuset SCHED_DEADLINE accounting can corrupt nr_deadline_tasks because scheduler updates and cpuset attach updates may modify the same counter under different locks. The corrupted counter can make later cpuset and deadline bandwidth operations use incorrect state, which may affect scheduling policy decisions and system availability. For the CVSS the PR:L is used in the paranoid score because reliable triggering may be possible for a local actor with delegated cgroup control, container root, service account privileges, or relevant scheduling capabilities rather than full host administrator privileges. The issue is not network reachable and requires local control plane activity involving sched_setscheduler and cpuset attach or migration. Impact is mainly denial of service or scheduling policy inconsistency. No concrete UAF, OOB access, information leak, or arbitrary write primitive is visible from this patch, so confidentiality impact is not assigned.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES SIMPLEFIX RACE LINUS NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 2
* Conservative score: 2. No floor or cap applied.
* Raw paranoid score: 3
* Paranoid score: 3. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Conservative positive signals:
* +1: concrete unsynchronized kernel accounting race. nr_deadline_tasks can be updated concurrently under different locks, so the counter can become incorrect.
* +1: plausible scheduling or availability impact. The corrupted counter is used for SCHED_DEADLINE cpuset accounting and root domain bandwidth update decisions, so wrong state can lead to incorrect later scheduler or cpuset operations.
Paranoid additional signal:
* +1: unresolved scheduler control-plane consequence. The commit states this is a partial low hanging fruit fix and does not cover all related races, so manual review of practical impact is justified.
Non-awarded signals:
* Real UAF not awarded. The patch does not show stale object use after free.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Kernel information disclosure not demonstrated.
* Concrete authorization bypass not demonstrated.
* Local unprivileged trigger not awarded because the complete sched_setscheduler plus cpuset attach or migration trigger path is not proven reachable by an ordinary user.
* Host-admin penalty not applied because host-admin-equivalent privilege is not positively established from the supplied evidence.
* Race penalty not applied because the prompt requires concrete evidence of a narrow or externally uncontrollable timing window, not merely the presence of a race.
* Extra availability point not awarded because no crash, panic, persistent host-wide outage, or resource exhaustion is demonstrated.
* Concrete repeated release/refcount signal not awarded. There is no first lifetime release, surviving exact dangling reference, or second lifetime mutation.
3. Reachability analysis
The likely trigger requires local control-plane activity involving SCHED_DEADLINE policy changes and cpuset task attach or migration. SCHED_DEADLINE operations commonly require elevated scheduling privilege such as CAP_SYS_NICE, and cpuset manipulation depends on cgroup delegation and controller permissions.
HostAdminRequired is UNKNOWN because the supplied patch does not prove that full host administrator privilege is required for the complete vulnerable sequence, but it also does not prove ordinary unprivileged reachability.
NamespaceScopedPrivilege is UNKNOWN. Cgroups and cpuset delegation may exist in some environments, but the supplied evidence does not establish that all required stages are attacker-reachable inside a namespace or delegated container context.
No direct network trigger is present. No special hardware requirement is present. The race is concurrent scheduler and cpuset accounting activity, but the supplied evidence does not establish a very hard one-shot timing condition.
4. Primitive and severity interpretation
The exact primitive is a data race on a scheduler/cpuset accounting counter. The bug can corrupt nr_deadline_tasks, which can then cause incorrect scheduler or cpuset decisions later.
This is not an active structured UAF and not fixed stale storage. It is a logic/accounting race with invalid kernel state. There is no concrete memory lifetime violation, no OOB access, no double free, no repeated refcount operation, and no demonstrated attacker-controlled kernel memory corruption.
PrimitiveClass is CLASS_C because the demonstrated issue is primarily corrupted accounting and invalid downstream behavior without an independently useful corruption primitive.
Demonstrated consequence: incorrect SCHED_DEADLINE cpuset accounting and possible incorrect later operations.
Speculative consequence: broader scheduling disruption or availability impact if the corrupted counter causes wrong root domain bandwidth handling. Privilege escalation is not supported by the supplied patch.
ImportantCandidate is NO because there is no Class A primitive and no strong Class B lifetime or corruption primitive requiring Important-vs-Moderate preservation.
AutoDowngradeAllowed is YES because the issue is an accounting race without demonstrated memory corruption, authorization bypass, concrete repeated lifetime mutation, or protected resource access. Manual review is still recommended because the affected area is scheduler/cgroup code and the fix is explicitly partial.
Likely operational severity: ordinary to borderline Moderate, not Important based on supplied evidence.
5. One-sentence report phrase
A race in cgroup cpuset SCHED_DEADLINE accounting can corrupt nr_deadline_tasks during concurrent scheduler and cpuset attach updates, causing incorrect scheduler state and possible local denial of service or policy inconsistency without a demonstrated UAF, arbitrary write, information leak, or privilege escalation primitive.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Reason: scheduler and cgroup accounting races can have non-obvious downstream effects, and the commit explicitly says this fix does not cover all related races, but the supplied patch does not establish a memory corruption or authorization-bypass primitive requiring mandatory Important-class review.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: cgroup/cpuset: Make nr_deadline_tasks an atomic_t [ Upstream
Commit: e422b32e6a57269ca8164c60674a78bee85cf5fb
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e422b32e6a57269ca8164c60674a78bee85cf5fb
Changed files:
kernel/cgroup/cpuset-internal.h
kernel/cgroup/cpuset.c
Diff excerpt:
Not included in this email. See the upstream URL for the full patch.
Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e422b32e6a57269ca8164c60674a78bee85cf5fb
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93150 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93150
The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.
The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.
This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.
The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.
Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:
Conservative CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
The Best / paranoid CVSS score: 5.3
The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.
CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.
A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.
Conservative ActionableScore: 2
Paranoid ActionableScore: 3
The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.
For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:
ActionableScore below 5 -> MODERATE REGULAR
ActionableScore 5 or more -> MODERATE 7.0
The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.
There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).
KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.
AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR
These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).
Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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