[CVE-2026-97456][MODERATE REGULAR] ACPICA: Fix condition check in acpi_ps_parse_loop() [ Upstream

[CVE-2026-97456][MODERATE REGULAR] ACPICA: Fix condition check in acpi_ps_parse_loop() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97456
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ACPICA: Fix condition check in acpi_ps_parse_loop() [ Upstream
Commit: a477c6ef5335d2d0613ff7c1779a8209f16627c5
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a477c6ef5335d2d0613ff7c1779a8209f16627c5
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97456
Analysis date: Thu, 24 Sep 2026 19:26:11 -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-2026-97456 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97456

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-2026-97456	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97456 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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-193;*CWE-20;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 acpi_ps_parse_loop can occur when the AML parser skips an invalid While or If block and dereferences the current AML pointer after it reaches the AML end pointer. A crafted AML stream can place the parser at the end of the AML buffer and cause a one byte read beyond the valid region. Depending on memory layout and fault handling this can result in a kernel warning or crash. For the CVSS the PR:H reflects that reliable triggering normally requires control of platform firmware, an ACPI table override, or equivalent administrative control over the boot environment. The issue is not directly network reachable. In virtualized deployments the affected kernel can consume ACPI tables supplied by the virtual firmware provider, which is normally a host to guest trust boundary. The demonstrated primitive is an out-of-bounds read and not a write. Impact is primarily denial of service. An information disclosure path is not demonstrated and should be manually reviewed.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	OOB DANGER SIMPLEFIX IMPROVEONLY  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

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

1. ActionableScore

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

2. Signal breakdown

* +1 Firmware-mediated external influence. The affected AML stream is normally supplied by platform firmware or a firmware-like ACPI table source.
* +1 Weak invalid-read concern. The patch establishes a concrete one-byte out-of-bounds read when the AML pointer reaches the end of the parser buffer.
* -2 Host-admin-equivalent prerequisite. Reliable malicious AML control normally requires firmware control, an ACPI table override, or equivalent boot-environment administration.
* No reliable kernel-crash point awarded. The supplied evidence supports a possible fault or warning depending on memory layout, but does not establish a reliable panic.
* No confidentiality point awarded. No copied-out data, user-visible disclosure, or sensitive-value influence is shown.
* No integrity point awarded. The affected operation is a read of an opcode byte, not a write or ownership mutation.
* No remote-reachability point awarded. Firmware-mediated AML input is not direct network traffic.
* No UAF, refcount mutation, controlled reclaim, arbitrary write, semantic reinterpretation, or authorization bypass is established.

3. Reachability analysis

A realistic attacker needs control over the AML supplied to the kernel. On native systems this normally means modifying platform firmware, controlling an ACPI table override during boot, or otherwise having host-admin-equivalent boot control.

The supplied patch does not establish an ordinary local-user path, a namespace-scoped capability path, or a network-triggerable path. In virtualized environments, virtual firmware may provide AML to a guest kernel, but this is normally a host-to-guest configuration boundary and does not establish guest-to-host reachability.

No race, special hardware dependency, or attacker-controlled object-reuse sequence is established.

4. Primitive and severity interpretation

The exact primitive is a bounded one-byte out-of-bounds read in `acpi_ps_parse_loop()` when `walk_state->aml` equals `parser_state->aml_end` and the parser tests for `AML_ELSE_OP`.

This is not a UAF, double free, stale-object use, refcount error, or write primitive. The shown access only reads an AML opcode byte beyond the valid AML range. Depending on adjacent mapping and parser state, it may cause a warning or fault, but the patch does not establish a controlled disclosure path, memory corruption, privilege escalation, or a security-boundary bypass.

The issue is therefore CLASS_C. It is not an Important candidate, and automatic downgrade is allowed after normal affected-version and deployment validation. Manual review remains recommended because ACPICA parser input can originate from firmware or virtual firmware and the actual result of an end-of-buffer access can vary by platform and memory layout.

5. One-sentence report phrase

A missing AML end-boundary check in `acpi_ps_parse_loop()` permits a one-byte out-of-bounds opcode read while processing malformed ACPI AML, but reliable triggering normally requires host-admin-equivalent firmware or boot-environment control and no write or disclosure primitive is demonstrated.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether the affected product permits attacker-controlled ACPI table overrides, mutable firmware input, or untrusted virtual-firmware AML. No urgent manual exploitability investigation is required if AML originates only from trusted platform firmware and boot configuration is protected.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ACPICA: Fix condition check in acpi_ps_parse_loop() [ Upstream
Commit: a477c6ef5335d2d0613ff7c1779a8209f16627c5
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a477c6ef5335d2d0613ff7c1779a8209f16627c5

Changed files:
  drivers/acpi/acpica/psloop.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=a477c6ef5335d2d0613ff7c1779a8209f16627c5

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

The original Linux kernel CVE announcement for CVE-2026-97456 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97456

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: 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).