[CVE-2026-93133][LOW] ACPI: RISC-V: Check acpi_get_handle() status in riscv_acpi_add_prt_dep() [ Upstream

[CVE-2026-93133][LOW] ACPI: RISC-V: Check acpi_get_handle() status in riscv_acpi_add_prt_dep() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93133
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ACPI: RISC-V: Check acpi_get_handle() status in riscv_acpi_add_prt_dep() [ Upstream
Commit: f8625752bfdf108a0000116aa583b3efe767b540
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8625752bfdf108a0000116aa583b3efe767b540
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93133
Analysis date: Thu, 17 Sep 2026 19:39:39 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
An unchecked `acpi_get_handle()` failure in RISC-V ACPI PRT dependency setup can leave `link_handle` uninitialized, making malformed firmware or ACPI table data capable of causing invalid dependency handling or a boot/probe-time DoS, but practical attacker control normally requires host-admin-equivalent firmware or ACPI override access.

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

The original Linux kernel CVE announcement for CVE-2026-93133 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93133

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-2026-93133	LOW	https://www.kernelcve.org/list/?q=CVE-2026-93133 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:L/I:L/A:H';CWE-252;*CWE-457;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.2';DESCR 'An unchecked acpi_get_handle failure in riscv_acpi_add_prt_dep can leave link_handle uninitialized and allow later dependency setup code to consume an invalid ACPI handle. The practical trigger depends on malformed or attacker controlled ACPI namespace data on a RISC-V ACPI system rather than network traffic. For the CVSS the PR:H is used because reliable triggering normally requires administrator level control over firmware data, boot configuration, or ACPI table override. The issue is not network reachable. Impact is primarily denial of service during ACPI device discovery or boot/probe paths. For the paranoid score, limited confidentiality or integrity impact is kept possible because an uninitialized kernel handle may cause invalid object access, but there is no clear arbitrary write primitive in the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)  SKIP CVE-2026-93133 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	SIMPLEFIX  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

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

## 1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score.

## 2. Signal breakdown

Positive signals:

* +1 Weak invalid object / uninitialized value use. `acpi_get_handle()` may fail and leave `link_handle` uninitialized, after which dependency setup may consume an invalid ACPI handle.
* +1 Plausible DoS / boot-probe failure. The likely consequence is invalid ACPI dependency construction or fault during ACPI device discovery.

Negative signals:

* -2 Host-admin-equivalent trigger requirement. Reliable attacker control appears to require firmware control, boot configuration control, or ACPI table override.

Non-awarded signals:

* No Real UAF. No freed object or stale post-lifetime use is established.
* No repeated release/refcount operation.
* No controlled reclaim or object replacement.
* No arbitrary or directed kernel write.
* No confidentiality or integrity impact awarded. The patch does not establish disclosure, protected-object access, or unauthorized modification.
* No remote reachability. This is ACPI table / firmware / boot-probe input, not network traffic.
* No namespace-scoped privilege. Namespaces are not involved.
* No Important-grade primitive. The issue is an unchecked return leading to an uninitialized handle, not a demonstrated memory corruption or authorization bypass.

## 3. Reachability analysis

The practical trigger depends on malformed or attacker-controlled ACPI namespace data on a RISC-V ACPI system. A normal local user cannot usually modify ACPI tables or firmware-provided namespace data. Reliable triggering normally requires administrator-level boot configuration, ACPI table override, firmware control, or equivalent platform control.

HostAdminRequired is YES because the complete attacker-controlled trigger path is tied to host firmware or boot-time ACPI configuration. NamespaceScopedPrivilege is NO because no namespace-scoped capability is relevant. No prior network exposure is present. No race condition or special timing is involved.

## 4. Primitive and severity interpretation

The primitive is unchecked error handling leading to use of an uninitialized `acpi_handle`. This is best treated as CLASS_C invalid-state behavior. It may cause a boot/probe-time crash or incorrect dependency handling, but the patch does not establish UAF, double free, refcount corruption, OOB access, controlled write, information leak, or privilege escalation.

ImportantCandidate is NO because there is no strong corruption, ownership, authorization, or boundary-bypass primitive. AutoDowngradeAllowed is YES because the issue is firmware/configuration-dependent, host-admin-gated, and lacks unresolved exploitation leverage beyond potential DoS.

Likely operational severity is Low-like / ordinary Moderate, mostly relevant for robustness of RISC-V ACPI boot and device enumeration.

## 5. One-sentence report phrase

An unchecked `acpi_get_handle()` failure in RISC-V ACPI PRT dependency setup can leave `link_handle` uninitialized, making malformed firmware or ACPI table data capable of causing invalid dependency handling or a boot/probe-time DoS, but practical attacker control normally requires host-admin-equivalent firmware or ACPI override access.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: no UAF, no concrete kernel corruption primitive, no network reachability, and reliable triggering appears host-admin or firmware controlled.

## 7. Call-site confidence

Call-site confidence: medium

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

Patch: ACPI: RISC-V: Check acpi_get_handle() status in riscv_acpi_add_prt_dep() [ Upstream
Commit: f8625752bfdf108a0000116aa583b3efe767b540
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8625752bfdf108a0000116aa583b3efe767b540

Changed files:
  drivers/acpi/riscv/irq.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=f8625752bfdf108a0000116aa583b3efe767b540

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

The original Linux kernel CVE announcement for CVE-2026-93133 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93133

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:L/I:L/A:H
  The Best / paranoid CVSS score: 5.2

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).