[CVE-2026-64013][MODERATE 7.0] ACPI: button: Fix ACPI GPE handler leak during removal [ Upstream

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

CVE: CVE-2026-64013
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ACPI: button: Fix ACPI GPE handler leak during removal [ Upstream
Commit: 614cb8c26c5aa53196ee9b211b76ee618b147d32
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=614cb8c26c5aa53196ee9b211b76ee618b147d32
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64013
Analysis date: Sun, 19 Jul 2026 23:12:02 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-64013 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64013

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-2026-64013	MODERATE	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:L/UI:N/S:U/C:L/I:L/A:H';*CWE-772;*CWE-416;*CWE-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'ACPI button driver removal can leave an ACPI notify handler registered because the handler was installed as ACPI_ALL_NOTIFY but removed as ACPI_DEVICE_NOTIFY. After driver removal, a later ACPI notify for the same device may call the leaked handler with driver private data that should no longer be live, which can cause a kernel crash and is a use-after-free candidate. For the CVSS the PR:L is used in the paranoid score because some systems may expose driver unbind, module removal, or ACPI device management to a local service account or container-like management context rather than only to a fully trusted administrator. The issue is not network reachable and normally requires a local control-plane action plus a later ACPI event. Impact is at least local denial of service via kernel crash, with limited confidentiality or integrity impact kept only for the paranoid interpretation because stale callback execution can dereference freed driver state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	OOB SIMPLEFIX LEAK KERNEL_PANIC_PLUS_UAF HARDWARE  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	guess

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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
* Weak/indirect corruption candidate: +1. The stale ACPI notify handler may be invoked after driver removal and can dereference driver state that should no longer be live.
* Real lifetime corruption: +1. This is a handler lifetime mismatch, not just a passive memory leak.
* Reliable kernel crash / strong DoS: +1. The commit explicitly says a kernel crash may occur if an ACPI notify is triggered after removal.
* Firmware-mediated external influence: +1 in paranoid scoring. The final trigger is an ACPI notify event, which can be firmware or platform mediated.
* Weak LPE concern: +1 in paranoid scoring only. The stale callback/UAF candidate justifies manual review, but no reclaim, overwrite, or controlled object replacement is demonstrated.
* Broad/default/common subsystem: +1. ACPI button/lid handling is common on many systems, especially laptops and ACPI-based platforms.
* Requires admin/root/CAP-like control in typical deployments: -2 conservative. Driver removal or unbind is usually privileged.
* Special trigger conditions: -1 paranoid. Exploitation needs driver removal plus a later ACPI notify on the affected device.

3. Reachability analysis
The realistic trigger requires local control over driver removal, module unload, device unbind, or similar ACPI/device-management operations, followed by an ACPI notify event. In normal deployments this is administrator-controlled, so the conservative score treats it as privileged. The paranoid score accounts for systems where device unbind or platform management may be exposed to a reduced-privilege service account, container-like management context, or automation layer rather than full trusted host root. This is not network reachable. Namespace impact is likely limited unless device-management privileges are delegated into a container. Call-site confidence: medium-high for the handler type mismatch and stale handler lifetime issue, medium for exploitability beyond crash because the provided diff does not show reclaim or attacker-controlled reuse.

4. Severity interpretation
This is more than an ordinary resource leak because it leaves an active callback registered after the driver object removal path. Realistic impact is local DoS through a kernel crash or failed reprobe. Theoretical memory-corruption concern exists due to stale callback execution, but the patch does not demonstrate a strong privilege-escalation primitive such as controlled reclaim, type confusion, arbitrary write, or refcount takeover. Therefore it is best treated as Actionable Moderate at minimum, not a clear Important-class issue.

5. One-sentence report phrase
An ACPI button notify handler installed as ACPI_ALL_NOTIFY was removed as ACPI_DEVICE_NOTIFY, leaving a stale handler after driver removal that can later be invoked by an ACPI event and cause a kernel crash or UAF-like stale callback condition.

6. Manual review recommendation
MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK. The stale callback after driver removal is a lifetime-safety issue and UAF candidate, even though the demonstrated impact is mainly local DoS and the trigger is normally privileged.

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

Patch: ACPI: button: Fix ACPI GPE handler leak during removal [ Upstream
Commit: 614cb8c26c5aa53196ee9b211b76ee618b147d32
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=614cb8c26c5aa53196ee9b211b76ee618b147d32

Changed files:
  drivers/acpi/button.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=614cb8c26c5aa53196ee9b211b76ee618b147d32

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

The original Linux kernel CVE announcement for CVE-2026-64013 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64013

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).