[CVE-2026-64014][MODERATE REGULAR] Input: usbtouchscreen - clamp NEXIO data_len/x_len to URB buffer size

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

CVE: CVE-2026-64014
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Input: usbtouchscreen - clamp NEXIO data_len/x_len to URB buffer size
Commit: 45c829e5eb3b974282bae50b7cca2cc891f74f0b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45c829e5eb3b974282bae50b7cca2cc891f74f0b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64014
Analysis date: Sun, 19 Jul 2026 15:02:38 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline actionable Moderate. Manual check required due device controlled kernel OOB read and user visible memory disclosure. Not Strong Important
Manual review required: YES

Summary:
A malicious NEXIO USB touchscreen can provide oversized length fields that make the usbtouchscreen driver read beyond its URB buffer, potentially leaking adjacent kernel memory through ABS_X / ABS_Y events and causing a kernel crash.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64014 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64014

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-2026-64014	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H';CWE-125;*CWE-20;*CWE-200;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H';BEST CVSS score: '6.1';DESCR 'An out of bounds read in the usbtouchscreen NEXIO parser occurs because data_len and x_len are taken from a device supplied packet header and were not bounded by the URB buffer size. A malicious or compromised USB touchscreen can advertise a length much larger than the 1024 byte transfer buffer, making nexio_read_data scan beyond packet data while looking for threshold crossings. The first matching bytes can influence ABS_X and ABS_Y input events, so adjacent kernel memory may be exposed to local userspace through reported touch coordinates, and a farther read can fault and crash the kernel. For the CVSS the PR:N because the attacker does not need an account on the target when they can control the attached USB device. The issue is not network reachable in normal deployments. Impact is confidentiality loss and denial of service, with no supported integrity or privilege escalation primitive from this patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline actionable Moderate. Manual check required due device controlled kernel OOB read and user visible memory disclosure. Not Strong Important (with actual score 3)  SKIP CVE-2026-64014 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB USB LEAK DMAorINTERRUPT HARDWARE LINUS PACKET  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline actionable Moderate. Manual check required due device controlled kernel OOB read and user visible memory disclosure. Not Strong Important**::

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1
  A malicious or compromised USB touchscreen can control the packet header fields consumed by the kernel driver.

* Confidentiality impact plausible: +1
  The commit explicitly describes adjacent kernel memory influencing ABS_X / ABS_Y events, creating a user-visible leak channel.

* Physical-only or rare hardware-only condition: -2
  The attacker generally needs control of an attached USB NEXIO-compatible touchscreen or equivalent malicious USB device.

* Practical leak path demonstrated or strongly implied: +1
  The OOB read result can be reflected through input coordinates, so this is more than a silent invalid read.

* Availability impact realistic: +1
  A sufficiently far OOB read can fault and crash the kernel, but this is secondary to the disclosure path.

Conservative total: 2

Paranoid additional interpretation:

* Stronger manual-review weight for device-controlled OOB read with kernel disclosure: +1
  The read can extend roughly 64 KiB past a DMA buffer and the commit describes a concrete user-visible disclosure path.

Paranoid total: 3

## 3. Reachability analysis

The bug is triggerable by a malicious or compromised USB touchscreen device that can lie about NEXIO data_len and x_len fields. No local user account is required if the attacker controls the physical USB device, but this is not network reachable. Namespaces and containers do not materially lower the trigger requirement because the vulnerable path is in the host kernel USB input driver and depends on device attachment rather than a normal local syscall API.

The path is not a broad default network or filesystem path. It depends on the usbtouchscreen NEXIO support and a matching device path, so real exposure is limited to systems where such USB input devices can be attached or emulated.

## 4. Severity interpretation

This behaves like an actionable Moderate issue rather than Important. The patch supports a concrete OOB read and information disclosure path, plus possible kernel crash, but it does not show an OOB write, UAF reclaim, type confusion, refcount abuse, arbitrary write, or privilege escalation primitive.

Theoretical severity is raised by kernel memory disclosure from a device-controlled length field. Realistic exploitation remains constrained by physical or device-level access and by the limited leak channel through input coordinates.

## 5. One-sentence report phrase

A malicious NEXIO USB touchscreen can provide oversized length fields that make the usbtouchscreen driver read beyond its URB buffer, potentially leaking adjacent kernel memory through ABS_X / ABS_Y events and causing a kernel crash.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is not just a crash-only bug. The patch and commit message describe a concrete kernel OOB read with a user-visible memory disclosure channel, so it should not be auto-closed even though exploitation requires physical or malicious-device access.

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

Patch: Input: usbtouchscreen - clamp NEXIO data_len/x_len to URB buffer size
Commit: 45c829e5eb3b974282bae50b7cca2cc891f74f0b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45c829e5eb3b974282bae50b7cca2cc891f74f0b

Commit description:

nexio_read_data() pulls data_len and x_len from a packed __be16 header
in the device's interrupt packet and then walks packet->data[0..x_len)
and packet->data[x_len..data_len) comparing each byte against a
threshold.

Both fields are 16-bit on the wire (max 65535).  The existing
adjustments shave at most 0x100 / 0x80 off, so the loop bound can still
reach roughly 0xfeff.  The URB transfer buffer for NEXIO is rept_size
(1024) bytes from usb_alloc_coherent(), with the first 7 occupied by the
packed header — so packet->data[] has 1017 valid bytes.  read_data()
callbacks are not given urb->actual_length, and nothing else bounds the
walk.

A device that lies about its length can get a ~64 KiB out-of-bounds read
past the coherent DMA allocation.  The first index whose byte exceeds
NEXIO_THRESHOLD lands in begin_x / begin_y and from there into the
reported touch coordinates, so adjacent kernel memory contents leak to
userspace as ABS_X / ABS_Y events.  Far enough out, the read can also
hit an unmapped page and fault.

Fix this all by clamping data_len to the buffer's data[] capacity and
x_len to data_len.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Fixes: 5197424 ("Input: usbtouchscreen - add NEXIO (or iNexio) support")
Cc: stable <stable@kernel.org>
Assisted-by: gkh_clanker_t1000
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/2026042026-chlorine-epidermis-fd6d@gregkh
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/input/touchscreen/usbtouchscreen.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=45c829e5eb3b974282bae50b7cca2cc891f74f0b

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

The original Linux kernel CVE announcement for CVE-2026-64014 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64014

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:L/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
  The Best / paranoid CVSS score: 6.1

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: 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).