[CVE-2026-93119][MODERATE 7.0] usb: ljca: bound bank_num in ljca_enumerate_gpio() [ Upstream

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

CVE: CVE-2026-93119
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: usb: ljca: bound bank_num in ljca_enumerate_gpio() [ Upstream
Commit: 0069593170a3d177de793c9a0b36989c4f069111
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0069593170a3d177de793c9a0b36989c4f069111
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93119
Analysis date: Thu, 17 Sep 2026 17:56:15 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A malicious LJCA USB device can report an excessive GPIO bank count and cause `ljca_enumerate_gpio()` to write beyond the local `valid_pin` stack array, leading to kernel stack corruption and at least a crash, with stronger impact requiring manual review.

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

The original Linux kernel CVE announcement for CVE-2026-93119 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93119

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-2026-93119	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93119 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:H/A:H';CWE-121;*CWE-787;*CWE-20;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.8';DESCR 'A stack based buffer overflow in the USB LJCA GPIO enumeration path can occur because ljca_enumerate_gpio trusts desc bank_num from the device more than the size of the local valid_pin array. A malicious or broken LJCA USB device can report a bank_num that passes the existing reply length and gpio_num checks while still causing the loop to write more u32 entries than valid_pin can hold. For the CVSS the PR:N because the attacker does not need an account on the target if they can present a crafted physical USB device. The issue is not network reachable and requires physical USB device access or an equivalent USB redirection path. Impact is at least denial of service via kernel crash and, because this is an attacker controlled stack overwrite in kernel code, the paranoid assessment should treat confidentiality and integrity impact as plausible and require manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	YES	USB SIMPLEFIX HARDWARE  KPANIC INCREASED_TO_MODERATE7_FROM_LOW_BASED_ON_GUESSCVSS_AND_ACTIONABLESCOREHIGHER4	YES	NO	checked

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

ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

## 1. ActionableScore

* Raw conservative score: 2
* Conservative score: 5
* Raw paranoid score: 4
* Paranoid score: 5
* Applied conservative floor/cap: manual review safety floor for controlled kernel stack overwrite, 2 -> 5
* Applied paranoid floor/cap: manual review safety floor for controlled kernel stack overwrite, 4 -> 5
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

## 2. Signal breakdown

Conservative signals:

* +2: Strong corruption primitive. The device-controlled `bank_num` allows writes past the two-entry `valid_pin[]` stack array.
* +1: Reliable kernel crash / strong DoS. A kernel stack overwrite in enumeration can realistically crash the kernel.
* +1: Device-mediated external influence. The attacker-controlled input comes from a USB LJCA device response.
* -2: Physical/device access required. The direct attack requires a malicious or broken physical USB LJCA device, or an equivalent USB redirection path.

Paranoid additional signal:

* +2: Strong exploitation leverage concern. The overflow writes multiple device-controlled `u32` values past a kernel stack array, so impact beyond crash is technically defensible enough for mandatory review.

Material non-awarded signals:

* RealUAF not awarded. This is an out-of-bounds stack write, not a lifetime bug.
* Remote network reachability not awarded. No network path is established.
* Arbitrary kernel read/write not demonstrated.
* Controlled reclaim not relevant.
* Confidentiality and integrity are not counted as demonstrated consequences in the conservative score, but the controlled stack overwrite prevents auto-downgrade.
* Extra Availability not awarded beyond the same crash/DoS effect.

## 3. Reachability analysis

The attacker model is a malicious or malfunctioning LJCA USB device that returns a crafted GPIO descriptor. No account or host-admin privilege on the target is required if the attacker can present the device to the system. The path is not namespace-scoped and does not depend on CAP_NET_ADMIN or another namespaced capability.

The vulnerable path requires the LJCA USB driver and a device that reaches `ljca_enumerate_gpio()`. This is not directly network reachable. Practical exposure is mainly physical USB access, malicious peripheral supply-chain risk, or USB/IP / device-redirection scenarios where a remote-controlled USB device is exposed to the host.

No race is involved. The overflow follows deterministically from accepting `bank_num` larger than `ARRAY_SIZE(valid_pin)`.

## 4. Primitive and severity interpretation

The exact primitive is an attacker-influenced stack-based out-of-bounds write in kernel code. `valid_pin[]` has two `u32` entries, while a crafted descriptor can make the loop write up to nine entries. This is active kernel memory corruption, not merely invalid state or a warning.

This is `CLASS_A` because the patch establishes a concrete attacker-influenced kernel stack overwrite. The demonstrated consequence is at least kernel crash / DoS. A stronger consequence such as privilege escalation is not demonstrated, but it remains plausible enough for manual analysis because the overwritten memory is on the kernel stack and the write values are device-derived.

ImportantCandidate=YES because controlled kernel stack corruption is an Important-class candidate even without a complete exploit chain. AutoDowngradeAllowed=NO because automatically treating it as ordinary Moderate would discard a concrete kernel corruption primitive.

Operationally, this is likely an actionable physical-device attack rather than a broad remote vulnerability.

## 5. One-sentence report phrase

A malicious LJCA USB device can report an excessive GPIO bank count and cause `ljca_enumerate_gpio()` to write beyond the local `valid_pin` stack array, leading to kernel stack corruption and at least a crash, with stronger impact requiring manual review.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: concrete attacker-influenced kernel stack overwrite is established, and impact beyond DoS cannot be safely excluded from the patch alone.

## 7. Call-site confidence

Call-site confidence: high

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

Patch: usb: ljca: bound bank_num in ljca_enumerate_gpio() [ Upstream
Commit: 0069593170a3d177de793c9a0b36989c4f069111
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0069593170a3d177de793c9a0b36989c4f069111

Changed files:
  drivers/usb/misc/usb-ljca.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=0069593170a3d177de793c9a0b36989c4f069111

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

The original Linux kernel CVE announcement for CVE-2026-93119 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93119

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:L/A:H
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.8

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: unknown
  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).