[CVE-2026-93082][LOW] firmware: arm_scmi: Unwind P2A receiver mailbox setup failure [ Upstream

[CVE-2026-93082][LOW] firmware: arm_scmi: Unwind P2A receiver mailbox setup failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93082
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: firmware: arm_scmi: Unwind P2A receiver mailbox setup failure [ Upstream
Commit: 4c2a5d72357e5c6743c23b59615da287140d9d31
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4c2a5d72357e5c6743c23b59615da287140d9d31
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93082
Analysis date: Fri, 18 Sep 2026 01:53:35 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93082 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93082

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: LOW
Manual review required: NO

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

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-93082	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93082 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:H/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'ARM SCMI mailbox setup can leak the already acquired primary P2A mailbox channel if the later P2A receiver channel request fails. The stale allocation can leave the channel busy and can make later probe attempts fail, which may break SCMI transport initialization or platform services that depend on SCMI. For the CVSS the PR:H is used because reliable triggering normally requires administrator control over driver probe, device binding, or platform firmware setup. The issue is not network reachable and is not triggered by packet traffic. Impact is denial of service through resource retention and failed device initialization, with no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	INIT SIMPLEFIX HARDWARE LINUS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	YES	NO	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: -1
* Conservative score: 0
* Applied conservative floor/cap: minimum score clamp -1 -> 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Concrete persistent kernel resource/reference leak. The primary P2A mailbox channel is acquired and not unwound if the later P2A receiver channel request fails.
* +1 Paranoid localized availability impact. A leaked busy mailbox channel can make later probe attempts fail and may break SCMI transport initialization or dependent platform services.

Negative signals:

* -2 Host-admin-equivalent trigger requirement. Reliable triggering appears tied to driver probe, device binding, probe deferral, platform firmware setup, or equivalent host administration control.

Non-awarded signals:

* Real UAF not awarded. No freed object is later dereferenced or mutated.
* Concrete repeated release/refcount not awarded. The bug is missing unwind of an acquired mailbox channel, not a second put/release on the same dangling reference.
* Strong DoS not awarded. No kernel crash, panic, or host-wide fatal failure is shown.
* Remote reachability not awarded. The path is firmware/mailbox probe setup, not packet or remote input processing.
* C/I impact not awarded. No disclosure, unauthorized write, privilege escalation, or security-boundary bypass is established.
* Controlled reclaim, arbitrary write, structured stale-object leverage, and LPE are not demonstrated.

3. Reachability analysis

The vulnerable path is reached during ARM SCMI mailbox channel setup. A successful primary P2A mailbox channel request is followed by a failed P2A receiver channel request. The old code returned immediately and left the primary channel allocated.

An ordinary local user is not shown to be able to trigger the complete sequence. Reliable triggering requires control over driver probe or reprobe, device bind or unbind behavior, platform firmware state, mailbox channel availability, or probe deferral conditions. This is host-admin-equivalent in the supplied context.

Namespace-scoped privilege does not apply. SCMI firmware transport and mailbox channels are platform resources, not attacker-created network namespace objects. No direct network reachability, sysctl-only user trigger, or unprivileged runtime API is established. Special platform firmware and SCMI mailbox configuration are prerequisites, but this does not create a remote or below-host-admin attacker path.

Race repeatability is not relevant. This is an ordered error-unwind bug, not a timing race.

4. Primitive and severity interpretation

The exact primitive is a missing resource unwind after partial mailbox setup failure. The primary channel remains allocated when the receiver channel request fails. This can leave the mailbox channel busy and cause later probe attempts to fail.

This is not active structured UAF, not fixed stale storage UAF, and not a repeated release/refcount mutation. The first operation acquires a resource, but there is no evidence that an object lifetime ends and the same dangling reference is later used again. The demonstrated consequence is failed initialization or localized denial of service for SCMI transport or dependent services.

PrimitiveClass is CLASS_C because the behavior is resource retention and invalid device initialization state without a memory corruption or authorization primitive. ImportantCandidate is NO because there is no unresolved meaningful exploitation leverage beyond resource leak and localized availability impact. AutoDowngradeAllowed is YES because the issue is host-admin-gated, non-remote, non-corrupting, and lacks UAF, double release, COW violation, security-boundary bypass, or controlled kernel corruption.

Likely operational severity is Low-like or ordinary Moderate depending on how critical SCMI is for the affected platform.

5. One-sentence report phrase

ARM SCMI mailbox setup can leak the already acquired primary P2A mailbox channel when the receiver channel request fails, leaving the channel busy for later probes and causing localized denial of service in SCMI initialization under host administrator controlled setup conditions.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch shows a straightforward resource unwind fix with no memory corruption, no UAF, no repeated lifetime mutation, no remote trigger, and no plausible privilege escalation path.

7. Call-site confidence

Call-site confidence: medium

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

Patch: firmware: arm_scmi: Unwind P2A receiver mailbox setup failure [ Upstream
Commit: 4c2a5d72357e5c6743c23b59615da287140d9d31
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4c2a5d72357e5c6743c23b59615da287140d9d31

Changed files:
  drivers/firmware/arm_scmi/transports/mailbox.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=4c2a5d72357e5c6743c23b59615da287140d9d31

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

The original Linux kernel CVE announcement for CVE-2026-93082 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93082

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: unknown
  Paranoid ActionableScore: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).