[CVE-2026-64363][MODERATE REGULAR] HID: appleir: fix UAF on pending key_up_timer in remove() [ Upstream

[CVE-2026-64363][MODERATE REGULAR] HID: appleir: fix UAF on pending key_up_timer in remove() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64363
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: HID: appleir: fix UAF on pending key_up_timer in remove() [ Upstream
Commit: 89ef67359672bf4cd6921524e39f61648fe38c0f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89ef67359672bf4cd6921524e39f61648fe38c0f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64363
Analysis date: Sat, 25 Jul 2026 11:44:16 -0400
ActionableScore: 4
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review required. Not an Important candidate on current evidence
Manual review required: YES

Summary:
A race in the HID appleir remove path can let a pending key_up_timer or concurrent raw_event dereference a freed input_dev after device teardown, causing a physical or device-mediated kernel UAF with likely DoS impact and limited but review-worthy escalation concern.

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

The original Linux kernel CVE announcement for CVE-2026-64363 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64363

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-64363	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A use-after-free race exists in the HID appleir remove path because hid_hw_stop can unregister and free input_dev before the pending key_up_timer or a concurrent raw_event path has stopped using it. A key event shortly before device disconnect can arm the timer, and a USB URB completion during teardown can also rearm the timer or call input reporting helpers while input_dev is being freed. For the CVSS the PR:N is used for the paranoid score because an attacker with physical access to a malicious or controllable Apple IR HID device does not need an OS account on the target, although reliable exploitation still requires a teardown timing race. The issue is not network reachable. Impact is at least local physical denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to kernel use-after-free memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review required. Not an Important candidate on current evidence (with actual score 3)	YES	LOCK USB INIT RACE UAF TIMER HARDWARE LINUS TEST PACKET  INCREASED_TO_MODERATE7_FROM_MODERATE_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=4
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 4
* Final recommended bucket: **Borderline manual review required. Not an Important candidate on current evidence**

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated or external device influence: +1
  A controllable Apple IR HID device can influence HID reports and timing, but this is not network reachable.
* Memory corruption, weak primitive: +1
  The bug is a race-dependent UAF on `input_dev`, but the patch does not show attacker-controlled reclaim, overwrite, type confusion, or callback target control.
* Real lifetime corruption: +1
  `hid_hw_stop()` can free `input_dev` while `key_up_timer` or `raw_event()` can still dereference it.
* Reliable kernel crash / strong DoS: +1
  A stale `input_dev` dereference through input reporting paths can plausibly crash the kernel.
* Availability impact realistic: +1
  If triggered, the effect is host kernel crash or serious kernel fault, not just a local process failure.
* Hard or unreliable race / special timing required: -1
  Triggering requires a disconnect/remove window while the timer or URB completion path is active.
* Physical-only or rare hardware-only condition: -2
  The affected path requires a specific Apple IR HID device or malicious compatible HID hardware and physical/device-level access.

Paranoid additions/changes:

* Weak LPE concern: +1
  The UAF involves stale timer and URB-completion paths calling into the input layer after object teardown, so manual review is justified even though no reclaim or write primitive is demonstrated.
* Race penalty relaxed: +1 relative to conservative
  A malicious or controllable HID device may repeatedly generate key events and disconnect timing, making the race more testable than a purely accidental teardown race.

Call-site confidence: high. The commit message and patch show the relevant call paths: `appleir_remove()`, `hid_hw_stop()`, `timer_shutdown_sync()`, `appleir_raw_event()`, and `key_up_tick()`.

## 3. Reachability analysis

The bug is not network reachable. It is reachable through a local physical or device-mediated path involving an Apple IR HID device or a malicious compatible HID device. No OS account is required if the attacker has physical control over the device path, but practical exploitation requires timing a key event, pending timer, URB completion, and device teardown. Namespaces and containers do not materially improve reachability because the key requirement is device presence and removal rather than a normal unprivileged syscall interface. The affected driver is device-specific and not a broad default attack surface on most systems.

## 4. Severity interpretation

This behaves like a physical/device-mediated kernel UAF with realistic DoS impact and limited evidence for exploitation beyond crash. Theoretical privilege escalation cannot be fully dismissed because the stale pointer is used after `input_dev` can be freed, but the patch does not show controlled reclaim, writable stale object access, type confusion, refcount takeover, or arbitrary write. Therefore it is not a Strong Important candidate on current evidence, but it should not be blindly auto-closed because it is a real kernel lifetime bug.

## 5. One-sentence report phrase

A race in the HID appleir remove path can let a pending key_up_timer or concurrent raw_event dereference a freed input_dev after device teardown, causing a physical or device-mediated kernel UAF with likely DoS impact and limited but review-worthy escalation concern.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a confirmed kernel UAF race involving asynchronous timer and URB-completion paths. The practical exposure is limited by physical or rare-device requirements, but memory lifetime bugs of this type require manual review before closure.

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

Patch: HID: appleir: fix UAF on pending key_up_timer in remove() [ Upstream
Commit: 89ef67359672bf4cd6921524e39f61648fe38c0f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89ef67359672bf4cd6921524e39f61648fe38c0f

Changed files:
  drivers/hid/hid-appleir.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=89ef67359672bf4cd6921524e39f61648fe38c0f

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

The original Linux kernel CVE announcement for CVE-2026-64363 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64363

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:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 2
  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).