[CVE-2026-64510][MODERATE 7.0] ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup [ Upstream

[CVE-2026-64510][MODERATE 7.0] ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64510
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup [ Upstream
Commit: ee82078e776ae31266cc70fdf62ac17c3c6f100a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ee82078e776ae31266cc70fdf62ac17c3c6f100a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64510
Analysis date: Sat, 25 Jul 2026 12:16:34 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An ACPI NFIT cleanup bug can leave a freed `acpi_desc` object in the global list after init failure or driver removal, allowing a later ACPI MCE to trigger a kernel use-after-free and likely DoS, with limited worst-case C/I concern but no demonstrated LPE primitive.

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

The original Linux kernel CVE announcement for CVE-2026-64510 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64510

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 7.0
Manual review required: YES

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

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-64510	MODERATE	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:L/I:L/A:H';*CWE-416;CWE-459;CWE-825;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'An ACPI NFIT cleanup bug can leave a freed acpi_desc object referenced from the global acpi_descs list after an init failure or driver removal path. A later ACPI Machine Check Exception can make nfit_handle_mce iterate that list and dereference the stale object, resulting in a kernel use after free. For the CVSS the PR:L is used for the paranoid score because some deployments may allow a local actor or reduced capability admin context to influence driver bind or remove paths, but reliable triggering still depends on an NFIT init failure or removal sequence and a later ACPI MCE. The issue is not network reachable. Base impact is denial of service via kernel crash. Worst case impact may include limited confidentiality or integrity risk because the bug class is use after free, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	OOB INIT RACE UAF HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* Generic memory corruption: +2. The commit explicitly describes a dangling `acpi_desc` pointer left in the global `acpi_descs` list and later dereferenced by `nfit_handle_mce()`, which is a kernel use-after-free.
* Real lifetime corruption: +1. The bug is a real object lifetime cleanup failure after init failure or driver removal.
* Reliable kernel crash / strong DoS: +1. A later ACPI MCE can traverse the stale list entry and trigger UAF, likely resulting in an Oops or panic.
* Firmware-mediated external influence: +1. The final trigger is an ACPI Machine Check Exception, which is hardware or firmware mediated rather than a normal local syscall path.
* Privileged kernel/device-management memory corruption path: +1. The corruption occurs in ACPI NFIT/NVDIMM device-management state and a global kernel list.
* Requires admin/root/CAP_* in typical deployments: -2. Reliable attacker influence over probe failure, driver removal, or NFIT device lifecycle normally requires privileged control or specific platform conditions.
* Rare AND difficult-to-reach subsystem/configuration: -1. ACPI NFIT/NVDIMM plus a subsequent ACPI MCE is not a broad default user-triggerable path.

Paranoid additions:

* Confidentiality impact plausible: +1. UAF may theoretically expose stale kernel object state if reuse is controllable, but no concrete leak primitive is shown.
* Integrity impact plausible: +1. UAF may theoretically corrupt logic through stale object reuse, but no attacker-controlled reclaim, write primitive, callback dispatch, or object replacement is demonstrated.

No LPE bonus is awarded. The patch supports UAF, but not controlled reclaim, type confusion, callback control, arbitrary write, or refcount takeover.

## 3. Reachability analysis

A normal unprivileged local user is unlikely to trigger this reliably. The bug requires an NFIT init failure or remove path that leaves `acpi_desc` on `acpi_descs`, followed later by an ACPI MCE that causes `nfit_handle_mce()` to iterate the list. In typical deployments, influencing NFIT driver bind/remove or the exact initialization failure path requires administrative privileges or platform-specific control.

Namespaces and containers do not materially lower the privilege requirement in ordinary configurations because ACPI platform device management is not normally delegated into unprivileged containers. The affected path is also hardware and configuration dependent, requiring ACPI NFIT/NVDIMM support and a later MCE event. Call-site confidence: high, because the commit explicitly identifies the stale list, the free path, and the later `nfit_handle_mce()` traversal.

## 4. Severity interpretation

This is stronger than an ordinary cleanup bug because it is an explicitly described kernel UAF in a global list. However, realistic exploitation appears constrained by rare hardware/platform conditions and privileged lifecycle control. The demonstrated practical impact is mainly local or firmware-mediated DoS. Theoretical memory corruption impact exists, but the supplied patch does not show a practical privilege-escalation primitive.

Overall this is an Actionable Moderate at minimum and should not be auto-closed solely as a low-risk DoS. It is not a strong Important candidate without additional evidence of attacker-controlled reclaim, object replacement, or a usable corruption primitive.

## 5. One-sentence report phrase

An ACPI NFIT cleanup bug can leave a freed `acpi_desc` object in the global list after init failure or driver removal, allowing a later ACPI MCE to trigger a kernel use-after-free and likely DoS, with limited worst-case C/I concern but no demonstrated LPE primitive.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED.

Reason: the bug is an explicit kernel use-after-free in ACPI/NVDIMM lifetime management, even though realistic triggering is hardware-dependent and likely privileged.

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

Patch: ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup [ Upstream
Commit: ee82078e776ae31266cc70fdf62ac17c3c6f100a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ee82078e776ae31266cc70fdf62ac17c3c6f100a

Changed files:
  drivers/acpi/nfit/core.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=ee82078e776ae31266cc70fdf62ac17c3c6f100a

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

The original Linux kernel CVE announcement for CVE-2026-64510 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64510

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:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 3
  Paranoid ActionableScore: 5

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 7.0

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).