[CVE-2026-97444][MODERATE REGULAR] ACPICA: add boundary checks in two places [ Upstream

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

CVE: CVE-2026-97444
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ACPICA: add boundary checks in two places [ Upstream
Commit: 253d7272d01db9529c79b95205c0f859ef9f4f23
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=253d7272d01db9529c79b95205c0f859ef9f4f23
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97444
Analysis date: Thu, 24 Sep 2026 17:43:22 -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-2026-97444 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97444

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.

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

CVE-2026-97444	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97444 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-193;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.1';DESCR 'An out of bounds read can occur in the ACPICA AML parser because acpi_ps_get_next_namestring and acpi_ps_peek_opcode did not consistently verify that AML data remained within aml_end before reading prefix, namestring, or extended opcode bytes. A malformed or truncated ACPI AML table can cause the kernel to read beyond the supplied AML buffer during ACPI table parsing. For the CVSS the PR:H rating is used because reliably providing malicious ACPI tables normally requires administrative control over ACPI table override mechanisms, the boot chain, or platform firmware. The issue is not directly network reachable. The realistic impact is parser failure or denial of service. The paranoid score allows limited confidentiality impact from the out of bounds read and high availability impact, but there is no demonstrated write primitive or supported privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	OOB DANGER IMPROVEONLY  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	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**::

The score reflects a parser boundary violation with firmware-mediated AML input, but no demonstrated disclosure, write, crash, or attacker-controlled table-delivery path below host administration.

2. Signal breakdown

* +1 Firmware-mediated external influence. ACPICA parses AML supplied by ACPI tables, which normally originate from platform firmware or another boot-time table source.
* +0 Limited OOB read. The patch establishes reads beyond `parser_state->aml_end`, but it does not establish a copy of adjacent bytes to userspace, network output, or another disclosure channel.
* +0 No reliable kernel crash or strong DoS awarded. The commit prevents out-of-bounds accesses but does not provide an Oops, panic, or demonstrated system-wide failure.
* +0 No confidentiality impact awarded. Internal out-of-bounds reads are not sufficient without a plausible read-back or disclosure path.
* +0 No integrity impact awarded. No write, active-object corruption, ownership violation, or authorization bypass is established.
* +0 No remote-reachability signal awarded. The parser consumes firmware-mediated AML and is not directly reachable through ordinary network traffic.
* +0 No local-unprivileged-trigger signal awarded. The supplied material does not establish that an ordinary local user can provide malicious ACPI AML to the vulnerable parser.
* +0 No host-admin penalty applied. Runtime ACPI table override commonly requires boot-chain or administrative control, but the supplied evidence does not fully establish every possible AML delivery path or prove host-admin privilege for all cases.
* +0 No rare-hardware or timing penalty applied. The issue is in generic ACPICA parsing and does not require a demonstrated hardware-specific race.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Real UAF or stale-lifetime use not demonstrated.
* Privilege escalation not demonstrated.
* Security-boundary bypass not demonstrated.

3. Reachability analysis

The vulnerable code parses AML from ACPI tables. The normal source is platform firmware, although ACPI tables can also be overridden through boot-time mechanisms in some configurations.

The supplied patch does not establish an ordinary local-user path for supplying a crafted AML table. It also does not establish a direct remote path. A malicious firmware image, compromised boot chain, privileged ACPI table override, or virtual-machine firmware configuration could provide malformed AML, but these represent materially different attacker models.

Host-admin-equivalent privilege is not positively established for every possible source of malformed AML, so `HostAdminRequired=UNKNOWN` is used. At the same time, below-host-admin reachability is not established, so `HostAdminRequired=NO` would be unsupported.

No namespace-scoped capability path is visible. No attacker-created namespace, device, sysctl, or runtime object is involved in the supplied patch. No race is involved.

4. Primitive and severity interpretation

The exact primitive is a bounded parser out-of-bounds read. `acpi_ps_get_next_namestring()` could advance past `aml_end` while consuming AML name prefixes or calculating a multi-segment name length. `acpi_ps_peek_opcode()` could read an opcode byte when AML is exhausted, including the second byte of an extended opcode.

This is not an active structured-object UAF, a double release, a refcount mutation, an out-of-bounds write, or a semantic ownership violation. The patch only adds bounds checks and parser failure handling.

The demonstrated consequence is invalid memory access beyond the logical AML buffer boundary. A parser failure or possible fault is plausible, but no reliable crash is demonstrated by the commit. A confidentiality consequence remains speculative because no path returns the adjacent bytes to an attacker. Integrity and LPE are unsupported because there is no write or control-flow primitive.

The primitive is therefore `CLASS_C`, not Class A or Class B. ImportantCandidate is `NO` because the evidence does not establish meaningful exploitation leverage beyond the invalid read. AutoDowngradeAllowed is `YES` because no unresolved lifetime, ownership, authorization, or active corruption primitive remains.

Likely operational severity is low to ordinary Moderate. Manual review is still useful to determine whether a specific product exposes attacker-controlled ACPI table override, virtual firmware, or firmware-update delivery paths.

5. One-sentence report phrase

Malformed ACPI AML can cause limited out-of-bounds reads in ACPICA parser functions, but the supplied patch does not establish a disclosure, write, privilege-escalation, or directly remote trigger primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Review product-specific ACPI table override, firmware-update, boot-chain, and virtualization firmware paths to determine whether an attacker below host administration can supply malformed AML.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ACPICA: add boundary checks in two places [ Upstream
Commit: 253d7272d01db9529c79b95205c0f859ef9f4f23
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=253d7272d01db9529c79b95205c0f859ef9f4f23

Changed files:
  drivers/acpi/acpica/psargs.c
  drivers/acpi/acpica/psparse.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=253d7272d01db9529c79b95205c0f859ef9f4f23

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

The original Linux kernel CVE announcement for CVE-2026-97444 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97444

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:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.1

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: 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).