[CVE-2026-74457][MODERATE REGULAR] can: peak_usb: add bounds check for USB channel index

[CVE-2026-74457][MODERATE REGULAR] can: peak_usb: add bounds check for USB channel index

[AL-KERNEL]

CVE: CVE-2026-74457
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: can: peak_usb: add bounds check for USB channel index
Commit: 825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457
Analysis date: Sat, 15 Aug 2026 08:51:31 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended / physical-device Moderate
Manual review required: YES

Summary:
A malicious or faulty PEAK PCAN-USB Pro compatible USB device can provide an out-of-range channel index that causes a heap out-of-bounds pointer read and invalid dereference in IRQ context, leading to a kernel crash.

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

The original Linux kernel CVE announcement for CVE-2026-74457 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457

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-2026-74457	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-129;CWE-125;*CWE-20;**CWE-476;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.7';DESCR 'A heap out-of-bounds read in the PEAK PCAN-USB Pro CAN driver occurs because ctrl_idx is derived from a USB device payload and only masked to 0-15 while usb_if dev has 2 entries. A malicious or faulty USB device can provide a channel index from 2 to 15, causing the driver to read past the device pointer array and later dereference an invalid pointer in IRQ context. For the CVSS the PR:N because the attacker does not need privileges on the host when the attack is modeled as a crafted USB device connected to the system. The issue is not network reachable and requires physical or equivalent USB device access. Impact is at least denial of service via kernel panic. The paranoid score keeps limited confidentiality and integrity impact because the primitive is a heap out-of-bounds read of a pointer followed by dereference, but the patch does not show an arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / physical-device Moderate (with actual score 3)	YES	OOB DANGER USB SIMPLEFIX NETWORK SKB HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	guess

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / physical-device Moderate**::

## 2. Signal breakdown

Triggered signals:

* Firmware-mediated or device-mediated external influence: +1
  The index comes directly from a USB device payload, so a malicious or faulty USB device can influence the vulnerable path.

* Memory corruption, weak/indirect corruption candidate: +1
  The bug is an unchecked array index into `usb_if->dev[]`, producing a heap out-of-bounds read of a pointer and later invalid object interpretation.

* Reliable kernel crash / strong DoS: +1
  The commit explicitly says values 2-15 eventually cause kernel panic in IRQ context.

* Privileged kernel/device-management memory corruption path: +1
  The corruption occurs in a kernel USB CAN driver receive/error path fed by device data.

Subtracted signals:

* Physical-only or rare hardware-only condition: -2
  Realistic triggering requires a malicious/faulty PEAK PCAN-USB Pro style USB device or equivalent USB device control.

* Rare AND difficult-to-reach subsystem/configuration: -1 in conservative view
  This is a device-specific CAN USB driver path, not a broadly exposed default kernel interface.

Paranoid adjustment:

* The paranoid score avoids the rare-subsystem subtraction because USB device parsing bugs with kernel OOB pointer reads deserve manual review even when hardware-specific.
* No strong LPE signal is awarded because the patch shows OOB read plus invalid pointer dereference, not controlled reclaim, arbitrary write, callback control, or object replacement.

## 3. Reachability analysis

The attacker can trigger the bug by controlling the USB payload received by the affected PEAK PCAN-USB Pro driver. This normally means physical access to attach a malicious USB CAN device, compromised device firmware, or an equivalent virtual/USB-over-IP setup. No local Linux user privileges are required on the host if the attacker controls the USB device, but this is not network reachable in the normal TCP/IP sense.

Namespaces and containers do not materially reduce the requirement, because the vulnerable input comes from hardware/device traffic rather than a namespaced local syscall API. The path is not default-exposed on most systems and requires the affected driver and matching hardware to be present.

Call-site confidence: high, because the patch shows both vulnerable dereferences before `alloc_can_skb()` and CAN error handling in the affected receive paths.

## 4. Severity interpretation

This behaves like an actionable physical-device Moderate rather than an Important-class kernel vulnerability. The theoretical concern is kernel memory safety, because a device-controlled index causes an out-of-bounds pointer read and bogus object dereference. The realistic demonstrated impact is kernel panic in IRQ context, i.e. host DoS.

There is not enough evidence for strong privilege escalation: no OOB write, no attacker-controlled replacement object, no callback dispatch, no refcount takeover, and no demonstrated information disclosure path. Manual review is still recommended because device-controlled OOB pointer reads in kernel drivers can sometimes hide stronger object-confusion consequences.

## 5. One-sentence report phrase

A malicious or faulty PEAK PCAN-USB Pro compatible USB device can provide an out-of-range channel index that causes a heap out-of-bounds pointer read and invalid dereference in IRQ context, leading to a kernel crash.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the practical exposure is limited by physical or equivalent USB device access, but the bug is still a device-controlled kernel heap OOB read followed by invalid object dereference, so it should not be auto-closed without confirming no stronger object-confusion or write-side consequences exist.

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

Patch: can: peak_usb: add bounds check for USB channel index
Commit: 825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f

Commit description:

The channel control index ctrl_idx is derived from rx->len which comes
directly from a device USB payload. The mask 0x0f allows values 0-15, but
the array size of usb_if->dev[] is only 2. Values 2-15 cause heap
out-of-bounds read, eventually causing kernel panic in the IRQ context.

Add bounds checking for ctrl_idx before the array access in both
pcan_usb_pro_handle_canmsg() and pcan_usb_pro_handle_error().

Fixes: d8a1993 ("can: usb: PEAK-System Technik PCAN-USB Pro specific part")
Signed-off-by: James Gao <jamesgao5@outlook.com>
Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/TYWPR01MB8559DBAAAA6A7F410400329CF0012@TYWPR01MB8559.jpnprd01.prod.outlook.com
Cc: stable@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/can/usb/peak_usb/pcan_usb_pro.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=825c903ca3c98cd0cf0e3de8ab8f2604a5339b3f

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

The original Linux kernel CVE announcement for CVE-2026-74457 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74457

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.7

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).