[CVE-2026-97450][LOW] ACPICA: validate handler object type in two places [ Upstream

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

CVE: CVE-2026-97450
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ACPICA: validate handler object type in two places [ Upstream
Commit: bfd981d35ed3156414fd35b4fe311d5d25cbfca6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bfd981d35ed3156414fd35b4fe311d5d25cbfca6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97450
Analysis date: Thu, 24 Sep 2026 19:40:15 -0400
ActionableScore: 1
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-2026-97450 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97450

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-2026-97450	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97450 CHECK WITH IMPACT FROM ORIG NN LOW	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-843;*CWE-20;CWE-704;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'ACPICA can access address handler fields while traversing a handler list without first verifying that each object has the ACPI_TYPE_LOCAL_ADDRESS_HANDLER type. An unexpected object type can cause invalid field interpretation and may result in an invalid pointer traversal or kernel crash. For the CVSS the PR:H reflects that influencing ACPI tables, AML, or platform firmware state normally requires administrative or equivalent platform control. The issue is not directly network reachable. Impact is primarily denial of service. Confidentiality and integrity impact are not claimed because the patch does not demonstrate an information leak, write primitive, use after free, or other memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	SIMPLEFIX HARDWARE 	NO	NO	checked

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

ActionableScore=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: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Weak indirect corruption candidate. The unpatched code interprets a handler-list element as an ACPI address-handler object without validating `handler_obj->common.type`. A non-handler operand object can therefore have fields interpreted under incompatible `address_space` semantics.
* No reliable kernel crash point. The patch prevents an invalid traversal, but the supplied commit does not document an observed Oops, panic, or reproducible crash.
* No UAF signal. There is no free, put, refcount decrement, RCU retirement, stale post-lifetime use, or repeated release operation in the supplied change.
* No controlled type-confusion or arbitrary write signal. The patch proves missing type validation, but does not establish attacker-controlled replacement object contents, pointer control, active-object corruption, or a write primitive.
* No remote-reachability point. ACPI firmware or AML mediated input is not direct attacker-controlled network traffic.
* No local-unprivileged-trigger point. The supplied evidence does not establish that an ordinary user can cause a malformed handler-list object.
* No host-admin penalty. Although ACPI table or firmware influence may require privileged platform control, this prerequisite is not fully established by the supplied patch and is recorded as unknown rather than assumed.
* No confidentiality or integrity point. No disclosure, unauthorized modification, protected-resource access, or security-boundary bypass is demonstrated.

3. Reachability analysis

The vulnerable path is reached while ACPICA traverses address-handler lists attached to namespace objects. The patch establishes only that a list entry can be of an unexpected operand-object type and that the old code would access it as an address handler.

The supplied context does not establish who can construct the malformed list state. In ordinary deployments, ACPI namespace objects, AML, and firmware tables are normally supplied by platform firmware or by trusted virtualization configuration. However, the complete attacker model is not visible here. It is therefore not justified to claim either host-admin-only reachability or ordinary-user reachability.

No namespace-scoped capability path, device interface, sysfs interface, table-loading path, virtual-machine configuration path, or firmware-mediated attacker path is supplied. There is no evidence of a race, repeatable lifetime manipulation, special hardware requirement, or direct network exposure.

4. Primitive and severity interpretation

The established primitive is an invalid structured-object interpretation. A valid `union acpi_operand_object` may be treated as an `ACPI_TYPE_LOCAL_ADDRESS_HANDLER` even when its actual type differs. This can cause reads of incompatible union fields and may cause traversal through a value interpreted as an address-handler list link.

This is not a real UAF. The patch does not establish that an object was freed, reused, replaced, or accessed after its lifetime ended. It also does not establish an out-of-bounds access, arbitrary pointer control, controlled reclaim, arbitrary write, callback dispatch, information disclosure, or privilege escalation.

The issue is classified as CLASS_C because the practical demonstrated concern is invalid-state processing that could plausibly result in an invalid dereference or crash if the malformed object state is reachable. The supplied patch does not establish an independently useful kernel-corruption primitive beyond that potential failure behavior.

ImportantCandidate is NO because the available evidence does not show meaningful exploitation leverage beyond invalid object interpretation. AutoDowngradeAllowed is YES because no concrete lifetime, authorization, ownership, write, disclosure, or security-boundary primitive remains unresolved.

5. One-sentence report phrase

Missing ACPICA handler object type validation could interpret a non-address-handler object as an address handler during list traversal, potentially causing invalid pointer processing and kernel denial of service if malformed ACPI object state is reachable.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The patch is a validation-only hardening change with no demonstrated crash or attacker-controlled source, but reviewing handler-list construction and ACPICA object-lifetime invariants would confirm whether an unexpected operand-object type can be induced from untrusted AML, firmware, or virtual-platform input.

7. Call-site confidence

Call-site confidence: low

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

Patch: ACPICA: validate handler object type in two places [ Upstream
Commit: bfd981d35ed3156414fd35b4fe311d5d25cbfca6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bfd981d35ed3156414fd35b4fe311d5d25cbfca6

Changed files:
  drivers/acpi/acpica/evhandler.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=bfd981d35ed3156414fd35b4fe311d5d25cbfca6

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

The original Linux kernel CVE announcement for CVE-2026-97450 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97450

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: 1

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).