[CVE-2026-68091][MODERATE REGULAR] HID: wacom: stop hardware after post-start probe failures

[CVE-2026-68091][MODERATE REGULAR] HID: wacom: stop hardware after post-start probe failures

[AL-KERNEL]

CVE: CVE-2026-68091
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: HID: wacom: stop hardware after post-start probe failures
Commit: 5a7ca028facf04921b2c1c2e4d1ee7f282510555
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a7ca028facf04921b2c1c2e4d1ee7f282510555
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68091
Analysis date: Mon, 10 Aug 2026 14:03:45 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A post-`hid_hw_start()` Wacom probe failure can release driver resources without stopping HID hardware first, leaving a possible stale hardware callback or resource lifetime window that may cause a physical-device-triggered kernel crash.

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

The original Linux kernel CVE announcement for CVE-2026-68091 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68091

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-2026-68091	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-404;*CWE-772;*CWE-416;CWE-703;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.3';DESCR 'A Wacom HID device probe can fail after hid_hw_start() has already started the HID hardware, while later error paths release Wacom driver resources without stopping the hardware first. This can leave callbacks or device activity running against resources that are being torn down, which is primarily a local or physical denial of service risk and a possible lifetime bug candidate. For the CVSS the PR:N is used in the paranoid score because a malicious or faulty HID device can trigger the probe error path without a local user account on the target. The issue is not network reachable and normally requires physical device access or an equivalent virtual HID path. Impact is at least denial of service via kernel crash or unstable device state, with limited confidentiality or integrity impact only in the paranoid interpretation due to possible use-after-free style lifetime exposure.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 2)	YES	USB SIMPLEFIX ERRORPATH HARDWARE LINUS TEST  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Conservative signals:

* Real lifetime corruption: +1. `hid_hw_start()` succeeds, then later probe steps may fail, and Wacom resources are released without stopping HID hardware first.
* Privileged kernel/device-management lifetime path: +1. The bug is in HID driver probe/error unwinding, where hardware callbacks and driver resources have coupled lifetimes.
* Physical-only or rare hardware-only condition: -2. Realistic triggering normally requires a Wacom HID device, a faulty device, malicious physical device, USB passthrough, or similar virtual HID path.

Paranoid additions:

* Memory corruption, weak/indirect corruption candidate: +1. The pattern can leave hardware activity or callbacks alive after resource teardown, which is a plausible stale-resource or UAF-style lifetime issue, but no controlled reclaim or write primitive is shown.
* Reliable kernel crash / strong DoS: +1. If callbacks or device activity continue after resource release, a crash or unstable device state is plausible.
* Broad/default-ish exposure: +1. HID auto-probe is common on desktop and workstation kernels, although Wacom-specific hardware is not universal.

No points awarded for:

* Remote/network reachability. No network path is shown.
* Strong LPE plausibility. No attacker-controlled reclaim, callback hijack, type confusion, arbitrary write, or refcount takeover is demonstrated.
* Confidentiality or integrity impact in the conservative score. These are only weak paranoid concerns.

## 3. Reachability analysis

The most realistic trigger is physical or device-mediated: attaching a faulty or malicious Wacom-compatible HID device, using USB/IP, VM passthrough, or another virtual HID injection path. A local user account is not necessarily required if the attacker controls the physical device, so PR:N can be defensible for CVSS-style physical attack modeling.

Namespaces and containers generally do not help much unless the attacker can influence USB/HID passthrough or device assignment. The affected path is not network reachable by ordinary packet traffic. The driver may be auto-loaded when matching hardware is attached, but triggering also depends on reaching one of the post-`hid_hw_start()` failure paths.

Call-site confidence: high, because the relevant error paths and cleanup ordering are visible in the patch.

## 4. Severity interpretation

This behaves more like a borderline Moderate hardware-lifetime bug than an Important-class vulnerability. The core issue is an incorrect probe failure unwind: started HID hardware may remain active while driver resources are released. That is enough for manual review because it resembles a stale callback or UAF-style lifetime pattern.

However, the realistic evidence supports DoS or unstable device state more strongly than privilege escalation. There is no demonstrated attacker-controlled reclaim, arbitrary write, callback control, or object replacement primitive. The conservative score therefore stays low, while the paranoid score reaches manual-review territory.

## 5. One-sentence report phrase

A post-`hid_hw_start()` Wacom probe failure can release driver resources without stopping HID hardware first, leaving a possible stale hardware callback or resource lifetime window that may cause a physical-device-triggered kernel crash.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is not remotely reachable and does not show a strong exploitation primitive, but it is a hardware lifetime cleanup bug with possible stale callbacks after resource release, so it should not be blindly auto-closed without checking whether HID callbacks can touch freed Wacom state.

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

Patch: HID: wacom: stop hardware after post-start probe failures
Commit: 5a7ca028facf04921b2c1c2e4d1ee7f282510555
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5a7ca028facf04921b2c1c2e4d1ee7f282510555

Commit description:

wacom_parse_and_register() starts HID hardware before registering inputs
and initializing pad LEDs/remotes. Those later steps can fail, but their
error paths currently release Wacom resources without stopping the HID
hardware.

Route post-hid_hw_start() failures through hid_hw_stop() before
releasing driver resources.

This issue was identified during our ongoing static-analysis research while
reviewing kernel code.

Fixes: c1d6708 ("HID: wacom: Do not register input devices until after hid_hw_start")
Cc: stable@vger.kernel.org
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/wacom_sys.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=5a7ca028facf04921b2c1c2e4d1ee7f282510555

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

The original Linux kernel CVE announcement for CVE-2026-68091 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68091

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:L/I:L/A:H
  The Best / paranoid CVSS score: 5.3

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: 1
  Paranoid ActionableScore: 3

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).