[CVE-2026-98363][MODERATE REGULAR] firmware: arm_scpi: reject DVFS OPP count above MAX_DVFS_OPPS [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-98363
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: firmware: arm_scpi: reject DVFS OPP count above MAX_DVFS_OPPS [ Upstream
Commit: e9887eeaa138c6b5697af3d2f7c71dc82407b154
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9887eeaa138c6b5697af3d2f7c71dc82407b154
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98363
Analysis date: Thu, 08 Oct 2026 06:06:24 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98363 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98363

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: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-98363	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98363 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (legacy and Aegis reconciliation differ; DECISION: legacy MODERATE vs Aegis MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';CWE-125;*CWE-20;CWE-1284;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'An out of bounds read in the ARM SCPI DVFS path occurs because scpi_dvfs_get_info trusted a firmware supplied opp_count larger than MAX_DVFS_OPPS. A malformed SCP firmware response can make the kernel read beyond the fixed buf.opps array and construct an OPP table using invalid data. For the CVSS the PR:H because an attacker must control or compromise the privileged SCP firmware or its trusted shared memory response. The issue is not network reachable through normal SCPI use. Impact is primarily availability through invalid DVFS data and possible platform instability. No confidentiality or integrity impact is demonstrated because the patch does not show an information disclosure primitive or an out of bounds write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	OOB SIMPLEFIX IMPROVEONLY LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

The conservative score uses the firmware-mediated input path only. The paranoid score additionally accounts for plausible availability impact if malformed OPP entries lead to unstable DVFS configuration. No floor or cap was applied.

2. Signal breakdown

* +1 Firmware-mediated external influence. The vulnerable `opp_count` originates in an SCP firmware shared-memory reply, and an invalid reply directly reaches the affected parsing path.
* +1 Paranoid only. Invalid OPP entries may be consumed by DVFS configuration code and can plausibly cause platform instability or failure of frequency and voltage management.

Important non-awarded signals:

* No UAF or stale lifetime reference is established.
* No controlled reclaim, object replacement, refcount corruption, callback control, or arbitrary write is demonstrated.
* No confidentiality point is awarded. The patch establishes an internal out-of-bounds read but no user-visible disclosure path.
* No integrity point is awarded. The patch does not establish an attacker-controlled write or unauthorized modification of protected state.
* No direct remote reachability is established. SCP firmware mediation is a material prerequisite.
* No reliable kernel crash is demonstrated by the supplied patch or commit message.
* No host-admin penalty is applied because controlling SCP firmware is security-sensitive but the complete privilege boundary for firmware modification or reply manipulation is not established.
* No niche or hardware penalty is applied solely because SCPI is platform firmware functionality.

3. Reachability analysis

The vulnerable path is reached when Linux queries DVFS information from ARM SCP firmware through the SCPI shared-memory protocol. The malformed value must come from the SCP firmware response or from manipulation of the trusted shared-memory exchange.

An ordinary local user is not shown to be able to generate or alter SCP replies. A normal network client also cannot directly reach this path. The complete attacker model is therefore unresolved and likely depends on a compromised SCP firmware component, a firmware update weakness, a malicious platform-management environment, or another lower-level compromise.

No relevant capability check or namespace-scoped interface is visible in the supplied context. This is not a namespace-reachable operation, and there is no evidence that an attacker-created user namespace or network namespace can complete the trigger chain. Prior platform support for ARM SCPI and an active DVFS domain are required, but no unsupported configuration penalty is applied.

4. Primitive and severity interpretation

The exact primitive is a firmware-controlled out-of-bounds read from the fixed-size `buf.opps[]` array when `opp_count` exceeds `MAX_DVFS_OPPS`. The unchecked count is then used when allocating and constructing an OPP table, allowing adjacent memory to be interpreted as additional OPP entries.

This is not a UAF, double free, refcount mutation, or active-object lifetime violation. It is also not an out-of-bounds write. The available evidence supports invalid-state handling and possible malformed DVFS data consumption, not controlled kernel memory corruption.

The issue is classified as CLASS_C because the established behavior is primarily an invalid read and invalid-state condition without an independently useful corruption, disclosure, authorization-bypass, or privilege-escalation primitive. A severe platform failure is plausible but not demonstrated in the supplied evidence.

ImportantCandidate is NO because no meaningful exploitation leverage beyond malformed firmware input and potential availability impact is established. AutoDowngradeAllowed is YES because the patch does not demonstrate an unresolved strong corruption or security-boundary primitive that would be lost by ordinary Moderate handling.

5. One-sentence report phrase

An ARM SCPI firmware reply with an out of range DVFS OPP count can cause the kernel to read beyond a fixed shared-memory response array and construct an invalid OPP table, potentially causing DVFS instability but without a demonstrated disclosure, write, or privilege-escalation primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The defect is a concrete out-of-bounds read in kernel firmware-response parsing, but practical attacker reachability depends on the platform-specific SCP firmware trust boundary and should be confirmed before prioritizing as a security issue.

7. Call-site confidence

Call-site confidence: medium

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: firmware: arm_scpi: reject DVFS OPP count above MAX_DVFS_OPPS [ Upstream
Commit: e9887eeaa138c6b5697af3d2f7c71dc82407b154
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9887eeaa138c6b5697af3d2f7c71dc82407b154

Changed files:
  drivers/firmware/arm_scpi.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=e9887eeaa138c6b5697af3d2f7c71dc82407b154

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98363 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98363

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:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.1

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: 1
  Paranoid ActionableScore: 2

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).