[CVE-2026-80766][MODERATE 7.0] HID: uclogic: fix use-after-free of inrange_timer on remove [ Upstream

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

CVE: CVE-2026-80766
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: HID: uclogic: fix use-after-free of inrange_timer on remove [ Upstream
Commit: f40243358b407aec362fe305fabfcdc94a3abd89
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f40243358b407aec362fe305fabfcdc94a3abd89
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80766
Analysis date: Fri, 04 Sep 2026 15:34:06 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in the HID uclogic remove path can rearm inrange_timer after timer_delete_sync(), allowing the timer callback to run after drvdata or pen_input is freed and causing a kernel use-after-free, with realistic impact of physical-device-triggered DoS and paranoid manual-review concern for broader memory-corruption impact.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-80766 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80766

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-2026-80766	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80766 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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 can occur in the HID uclogic remove path because timer_delete_sync() does not prevent inrange_timer from being rearmed by an in flight pen report before hid_hw_stop() stops the transport. A malicious or unstable HID tablet can keep delivering reports during device removal and rearm the timer, so the timer may fire after drvdata or the input device has been freed. For the CVSS the PR:N because the physical device based scenario does not require a local account on the victim, only the ability to interact with the HID transport. The issue is not network reachable and is best modeled as AV:P with AC:H due to the required teardown race window. Impact is at least denial of service via kernel crash, and the paranoid score treats the kernel UAF as possible memory corruption with C:H/I:H/A:H for manual review sensitivity.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	USB INIT UAF TIMER HARDWARE LINUS KPANIC  KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS 	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, weak primitive: +1. The patch describes a real UAF, but it is race dependent and no attacker controlled reclaim, overwrite, type confusion, or arbitrary write is shown.
* Real lifetime corruption: +1. The timer can be rearmed after timer_delete_sync(), then fire after drvdata or pen_input lifetime ended.
* Reliable kernel crash / strong DoS: +1. The stale timer callback can dereference freed memory in timer softirq context.
* Hard or unreliable race / special timing required: -1. Triggering requires a report to land in the remove window before hid_hw_stop().
* Physical-only or rare hardware-only condition: -2. The realistic attacker model is a malicious or unstable HID tablet or physical HID transport interaction.

Paranoid additional signals:

* Privilege escalation plausible, weak LPE concern: +1. The primitive is a kernel UAF in an async timer callback path, which deserves manual review even without demonstrated reclaim.
* Confidentiality impact plausible: +1. Only in paranoid mode, because freed kernel object reuse could theoretically expose non-DoS impact.
* Integrity impact plausible: +1. Only in paranoid mode, because UAF reuse could theoretically affect kernel object state.
* Broad/default/common subsystem exposure: +1. HID input is a common kernel subsystem, although this specific driver and device class narrow exposure.

## 3. Reachability analysis

The most realistic trigger is physical or device-mediated. An attacker would need to attach or control a uclogic-compatible HID tablet, or otherwise influence HID reports during device removal. No network reachability is present.

For the CVSS the PR:N is defensible for the physical-device scenario because no local user account is required if the attacker controls the attached HID device. A local software-only trigger such as driver unbind would usually require elevated privileges. Namespaces do not materially lower the physical attack requirement.

The path is not universally exposed on all systems. It depends on the HID uclogic driver and matching hardware or emulated device behavior.

## 4. Severity interpretation

This is not an ordinary cleanup bug because the patch fixes an explicit timer lifetime UAF. Realistic impact is most likely kernel crash or local physical DoS. Theoretical escalation risk exists because the stale timer callback dereferences freed kernel memory, but the patch does not show controlled reclaim, attacker-selected replacement object, arbitrary write, or type confusion.

Therefore this is best treated as Actionable Moderate for triage, not a strong Important candidate by default.

## 5. One-sentence report phrase

A race in the HID uclogic remove path can rearm inrange_timer after timer_delete_sync(), allowing the timer callback to run after drvdata or pen_input is freed and causing a kernel use-after-free, with realistic impact of physical-device-triggered DoS and paranoid manual-review concern for broader memory-corruption impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.

Reason: explicit kernel UAF plus async timer callback lifetime semantics, even though realistic exploitation is constrained by physical access and a narrow race window.

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

Patch: HID: uclogic: fix use-after-free of inrange_timer on remove [ Upstream
Commit: f40243358b407aec362fe305fabfcdc94a3abd89
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f40243358b407aec362fe305fabfcdc94a3abd89

Changed files:
  drivers/hid/hid-uclogic-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=f40243358b407aec362fe305fabfcdc94a3abd89

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

The original Linux kernel CVE announcement for CVE-2026-80766 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80766

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: 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: YES
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).