[CVE-2026-97448][MODERATE REGULAR] ACPICA: Add validation for node in acpi_ns_build_normalized_path() [ Upstream

[CVE-2026-97448][MODERATE REGULAR] ACPICA: Add validation for node in acpi_ns_build_normalized_path() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97448
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ACPICA: Add validation for node in acpi_ns_build_normalized_path() [ Upstream
Commit: babb146ceb79e71f328788f1e2c8c7c224026e61
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=babb146ceb79e71f328788f1e2c8c7c224026e61
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97448
Analysis date: Thu, 24 Sep 2026 18:19:58 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97448 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97448

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: YES

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

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

CVE-2026-97448	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97448 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:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-843;*CWE-20;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use after free risk exists in acpi_ns_build_normalized_path because the function may process an ACPI namespace node after that node is no longer a valid named descriptor. Dereferencing a stale node while constructing a normalized namespace path can cause a kernel crash and may have broader confidentiality or integrity impact if freed memory is reused in a controllable way. For the CVSS the PR:L is used for the paranoid score because a reduced capability local service account or container context may be able to reach an ACPI related interface in some deployments. Reliable triggering still requires a stale namespace node and a suitable lifetime timing condition. The issue is not directly network reachable. Impact is at least local denial of service. The UAF nature of the bug justifies manual analysis for potential memory corruption impact.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4)	YES	UAF  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	NO	NO	checked

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

ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 4
* Raw paranoid score: 2
* Paranoid score: 4
* Applied conservative floor: 2 -> 4. The patch directly identifies a UAF prevention condition, the stale node is actively dereferenced and traversed, and host-admin-equivalent privilege is not positively established.
* Applied paranoid floor: 2 -> 4.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +2 Real UAF or lifetime violation. The commit explicitly states that the node validation prevents use-after-free vulnerabilities. Before the fix, acpi_ns_build_normalized_path can dereference and traverse a node that is no longer a valid ACPI_DESC_TYPE_NAMED namespace node.
* +0 Reliable kernel crash or strong DoS. A stale node dereference can plausibly fault, but the supplied patch contains no crash report, reproducer, or evidence that a crash is reliable.
* +0 Remote reachability. No network-triggerable path is established.
* +0 Local unprivileged trigger. The supplied material does not identify a complete below-host-admin caller path.
* +0 Controlled reclaim or replacement. No evidence shows attacker control of allocation reuse, replacement-object contents, or reuse at the stale node address.
* +0 Structured stale-object exploitation leverage. Although an ACPI namespace node is structured, the visible stale use is a read-oriented normalized-path traversal. No callback, pointer redirection, refcount mutation, write, object replacement, or security-sensitive field consumption is established.
* +0 Concrete repeated release or refcount mutation. The patch adds validation before traversal and shows no second put, free, release, or refcount operation on the same stale reference.
* +0 Confidentiality and integrity impact. No disclosure path, write primitive, protected-object modification, or authorization bypass is established.
* +0 Paranoid exploitation bonus. The patch establishes a UAF candidate, but does not establish controlled reuse, arbitrary read or write, callback influence, or another attacker-useful post-free primitive.

3. Reachability analysis

The visible patch changes an ACPICA helper that receives an acpi_namespace_node pointer and constructs a normalized namespace path. The supplied context does not show the callers, the node lifetime transition, or the source of the stale pointer.

ACPI namespace creation, dynamic table loading, namespace teardown, and many ACPI control paths can be host-admin-controlled, firmware-mediated, or kernel-internal. However, the available evidence does not prove that the complete trigger requires host-admin-equivalent privilege. Therefore HostAdminRequired is UNKNOWN rather than YES.

No evidence establishes that an ordinary local user, container root, or a user with namespace-scoped capability can execute the complete stale-node lifetime sequence. NamespaceScopedPrivilege is UNKNOWN. No direct remote network path, special device prerequisite, firmware compromise requirement, or narrow race timing requirement is established by the patch.

4. Primitive and severity interpretation

The patch-supported primitive is a stale ACPI namespace node use. acpi_ns_build_normalized_path first reads the descriptor type and then traverses the namespace-node hierarchy. The added ACPI_DESC_TYPE_NAMED check indicates that callers may pass a node that has ceased to be a valid named namespace descriptor.

This is a real Class B lifetime primitive because the patch explicitly identifies UAF prevention and the old code actively consumes the potentially stale object. It is not Class A because no controlled reclaim, attacker-controlled replacement object, arbitrary or directed write, refcount takeover, callback dispatch, disclosure, or privilege escalation is established.

The stale object is a structured ACPI namespace object, but the shown operation is limited to path construction and parent traversal. The patch does not demonstrate a concrete second lifetime mutation or meaningful post-reuse structured processing beyond the dereference. The practical demonstrated consequence is therefore a possible local kernel fault or DoS, not confidentiality, integrity, or privilege escalation.

ImportantCandidate is NO because the available evidence supports a constrained stale-object dereference without demonstrated reuse leverage. AutoDowngradeAllowed is YES because no unresolved repeated release, active post-free mutation, security-boundary bypass, controlled corruption, or attacker-controlled object replacement is established. Manual review remains recommended because the patch explicitly labels the defect as UAF prevention and caller/lifetime context is absent.

5. One-sentence report phrase

A stale ACPI namespace node may be dereferenced during normalized path construction, creating a potential local kernel crash condition, while no controlled reuse, write primitive, or privilege escalation path is established by the supplied patch.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The patch explicitly addresses a use-after-free condition, but the supplied diff does not include callers, node destruction paths, attacker reachability, or evidence of controlled post-free reuse.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ACPICA: Add validation for node in acpi_ns_build_normalized_path() [ Upstream
Commit: babb146ceb79e71f328788f1e2c8c7c224026e61
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=babb146ceb79e71f328788f1e2c8c7c224026e61

Changed files:
  drivers/acpi/acpica/nsnames.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=babb146ceb79e71f328788f1e2c8c7c224026e61

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

The original Linux kernel CVE announcement for CVE-2026-97448 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97448

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:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 4

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).