[CVE-2026-89999][MODERATE 7.0] HID: wacom: validate report length in wacom_intuos_pro2_bt_irq

[CVE-2026-89999][MODERATE 7.0] HID: wacom: validate report length in wacom_intuos_pro2_bt_irq

[AL-KERNEL]

CVE: CVE-2026-89999
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: HID: wacom: validate report length in wacom_intuos_pro2_bt_irq
Commit: d2844f3fcd058113acbe0aa110ab13ef28b98d9f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d2844f3fcd058113acbe0aa110ab13ef28b98d9f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89999
Analysis date: Wed, 16 Sep 2026 14:30:02 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89999 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89999

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-89999	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-89999 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:L';CWE-125;CWE-126;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N';BEST CVSS score: '6.3';DESCR 'An out-of-bounds read in the Wacom Bluetooth report parser can occur because wacom_intuos_pro2_bt_irq uses fixed offsets in wacom data without first validating the received report length. A malicious or malfunctioning paired Bluetooth peripheral can advertise a matching VID/PID and send an undersized report that still passes the report id gate, causing the driver to read beyond the received report. The leaked bytes can be forwarded to userspace through evdev fields such as MSC_SERIAL, ABS_MISC, or ABS_WHEEL, giving this bug a concrete read back path rather than only a crash symptom. For the CVSS the PR:N is used for the paranoid score because the attacker controlled Bluetooth peripheral does not need a local account or kernel privileges on the victim system. The issue is adjacent network reachable over Bluetooth rather than Internet reachable, and practical exploitation usually requires proximity and a paired or spoofed HID device. Impact is primarily information disclosure, with possible limited availability impact if the invalid read hits protected memory or diagnostic hardening.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate (with actual score 5)	YES	OOB USB LINUS KPANIC  KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS 	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 4
* Conservative score: 4. No floor or cap applied.
* Raw paranoid score: 5
* Paranoid score: 5. No floor or cap applied.
* Final recommended bucket: **Actionable Moderate**::

2. Signal breakdown

Conservative positive signals:

* +1 Firmware or adjacent-device mediated external influence. A malicious or malfunctioning Bluetooth HID peripheral can supply the malformed report.
* +1 Concrete invalid read primitive. The parser reads fixed offsets from wacom->data without validating len.
* +1 Confidentiality plausible. The supplied context states that bytes read past the received report can be forwarded to userspace through evdev fields such as MSC_SERIAL, ABS_MISC, or ABS_WHEEL.
* +1 Practical trigger-to-disclosure chain. The input describes a concrete sequence: spoof or pair as matching VID/PID, send undersized report passing the report-id gate, trigger OOB read, observe values through evdev.

Paranoid additional signal:

* +1 Higher review sensitivity for meaningful disclosure. The supplied context says this can be a true OOB read when the backing buffer is sized to the small report descriptor, and repeated malformed reports may expose meaningful stale data through the evdev read-back path.

Non-awarded signals:

* RealUAF not awarded. No post-lifetime object use is established.
* Controlled reclaim not demonstrated.
* Arbitrary or directed kernel write not demonstrated.
* Strong LPE or privilege escalation not demonstrated.
* CLASS_A not used because the disclosure path is concrete but appears constrained by fixed parser fields and is not shown to be a broad arbitrary kernel read.
* Reliable kernel crash not awarded conservatively. Availability impact is possible in hardened or unlucky layouts, but the main established impact is information disclosure.
* Remote Internet reachability not awarded. The attack surface is Bluetooth adjacent, not ordinary IP network traffic.
* Race or timing penalty not applied. This is malformed input parsing, not a timing race.
* Hardware rarity penalty not applied. The issue is device specific, but Bluetooth HID tablets are not treated as rare physical-only hardware for scoring.

3. Reachability analysis

The plausible attacker is a malicious, spoofed, or malfunctioning Bluetooth HID peripheral that can advertise a matching Wacom VID/PID and send an undersized report. The attacker does not need host administrator privileges or a local user account on the victim system, but practical exploitation generally requires Bluetooth proximity and a successful pairing or spoofed trusted device scenario. User interaction may be involved depending on the Bluetooth pairing model.

No namespace capability is relevant. This is not a container or network namespace path. No host CAP_SYS_ADMIN or CAP_NET_ADMIN prerequisite is established for the attacker. Prior host setup may exist only in the ordinary sense that the HID Bluetooth device must be accepted by the system and the relevant Wacom driver path must be active.

The trigger is repeatable by sending malformed reports. No race window is required.

4. Primitive and severity interpretation

The exact primitive is a bounded out-of-bounds read from the HID report buffer caused by missing length validation before fixed-offset parsing. This is not a UAF, not a double release, and not a write corruption primitive. The stale or out-of-bounds bytes can be transformed into observable userspace input events, so this is stronger than an internal-only invalid read.

PrimitiveClass is CLASS_C because the established primitive is an invalid read with disclosure potential, not an active lifetime corruption or controlled kernel corruption primitive. The demonstrated consequence is information disclosure through evdev. A limited availability effect is plausible if the OOB read faults or hits hardening diagnostics, but that is not the primary conservative consequence.

ImportantCandidate is NO because there is no controlled write, controlled reclaim, privilege escalation, authorization bypass, or broad arbitrary kernel read. AutoDowngradeAllowed is NO because there is a concrete user-visible disclosure path and the issue should not be automatically closed as crash-only or harmless.

Likely operational severity is Actionable Moderate. It deserves manual review to determine whether real deployments expose meaningful stale kernel bytes through the relevant evdev fields and whether pairing requirements significantly reduce practical risk.

5. One-sentence report phrase

A missing report length check in wacom_intuos_pro2_bt_irq allows a malicious Bluetooth HID peripheral to send undersized Wacom reports that cause fixed-offset out-of-bounds reads, with leaked values potentially observable through evdev input events.

6. Manual review recommendation

MANUAL CHECK REQUIRED

The bug has a concrete OOB read and a supplied userspace read-back path, but the real-world severity depends on Bluetooth pairing, HID buffer sizing, evdev access, and whether repeated malformed reports expose sensitive stale data.

7. Call-site confidence

Call-site confidence: high

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

Patch: HID: wacom: validate report length in wacom_intuos_pro2_bt_irq
Commit: d2844f3fcd058113acbe0aa110ab13ef28b98d9f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d2844f3fcd058113acbe0aa110ab13ef28b98d9f

Commit description:

wacom_intuos_pro2_bt_irq() receives the wire report length in `len`
but never consults it before parsing. After the report-id gate it
unconditionally calls wacom_intuos_pro2_bt_pen() and then, selected by
features.type, a fixed chain of sub-parsers, none of which receive
`len`:

	wacom_intuos_pro2_bt_pen(wacom);
	if (type == INTUOSP2_BT || type == INTUOSP2S_BT) {
		wacom_intuos_pro2_bt_touch(wacom);
		wacom_intuos_pro2_bt_pad(wacom);
		wacom_intuos_pro2_bt_battery(wacom);
	} else {
		wacom_intuos_gen3_bt_pad(wacom);
		wacom_intuos_gen3_bt_battery(wacom);
	}

Each sub-parser dereferences wacom->data at fixed offsets. The furthest
byte touched on each branch is:

  INTUOSP2_BT / INTUOSP2S_BT: wacom_intuos_pro2_bt_pad() reads data[285]
	(the touchring byte), so the report must be at least 286 bytes;
  INTUOSHT3_BT ("gen3"): wacom_intuos_gen3_bt_battery() reads data[45],
	so the report must be at least 46 bytes.

features.type is selected from the VID/PID id_table entry and
wacom_setup_device_quirks() force-registers the pen/pad/touch inputs
for that type independent of the report descriptor, so a malicious or
malfunctioning paired/spoofed Bluetooth peripheral can advertise that
VID/PID and send an undersized report that still satisfies the
data[0] == 0x80/0x81 gate. The driver then reads past the received
report and forwards the bytes to userspace via evdev (MSC_SERIAL /
ABS_MISC / ABS_WHEEL on the pen and pad input nodes), an out-of-bounds
read with a concrete userspace read-back channel, and a true
out-of-bounds read on transports whose backing buffer is sized to the
(small) report descriptor rather than a fixed-size staging buffer.

This is the same class of bug commit 2f1763f ("HID: wacom: fix
out-of-bounds read in wacom_intuos_bt_irq") already hardened in the
sibling wacom_intuos_bt_irq(), which guards each report id against its
minimum length before parsing.

Guard wacom_intuos_pro2_bt_irq() the same way: before parsing, reject
reports shorter than the furthest offset the selected branch actually
dereferences, warn, and bail out. Because the whole pen/touch/pad/
battery chain runs unconditionally per branch, a single up-front check
against the maximum offset (286 bytes for INTUOSP2_BT/INTUOSP2S_BT,
46 bytes for the gen3 branch) bounds every sub-parser. Returning 0 on
a short report also skips those calls for the same malformed report,
which is the safe, conservative behavior.

Fixes: 4922cd2 ("HID: wacom: Support 2nd-gen Intuos Pro's Bluetooth classic interface")
Cc: stable@vger.kernel.org
Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Assisted-by: AuditCode-AI:2026.07
Acked-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/wacom_wac.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=d2844f3fcd058113acbe0aa110ab13ef28b98d9f

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

The original Linux kernel CVE announcement for CVE-2026-89999 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89999

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:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:L
  The Best / paranoid CVSS score: 6.3

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: 4
  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).