[CVE-2026-80706][MODERATE 7.0] can: softing: fw_parse(): validate firmware record spans

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

CVE: CVE-2026-80706
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: can: softing: fw_parse(): validate firmware record spans
Commit: f6d9a6a9512430b395a1940d7b216394fd02d30b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6d9a6a9512430b395a1940d7b216394fd02d30b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80706
Analysis date: Fri, 28 Aug 2026 04:25:47 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A malformed Softing CAN firmware image can make the firmware parser read beyond the firmware blob and use attacker influenced record addresses and lengths for out-of-bounds DPRAM/MMIO writes, causing at least local DoS and possible device state corruption.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-80706 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80706

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-2026-80706	MODERATE	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-125;*CWE-787;CWE-190;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'The Softing CAN firmware loader parses firmware supplied records without fully validating that the header, payload, and trailing checksum are inside the firmware blob. A malformed or truncated firmware image can make fw_parse read beyond the firmware buffer, and attacker controlled record addresses and lengths can also drive writes outside the intended DPRAM span through memcpy_toio. For the CVSS the PR:L is used for the paranoid score because systems with delegated device or firmware management may allow a less privileged local actor to trigger firmware load paths, while the base score keeps PR:H for normal admin controlled firmware installation. The issue is not network reachable and requires local ability to influence the firmware image or firmware loading path on a system with the affected Softing CAN hardware. Impact is at least local denial of service via kernel fault or device state corruption, and in the worst case may allow confidentiality or integrity impact due to out-of-bounds reads and writes to mapped I/O space.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	OOB NETWORK LINUS  DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1. The vulnerable input is a firmware image parsed by the Softing CAN driver.
* Constrained kernel or device buffer overwrite: +1. Firmware-controlled address and length fields can drive memcpy_toio outside the intended DPRAM span, but the target is device mapped memory rather than an obvious arbitrary kernel heap object.
* Privileged kernel/device-management memory corruption path: +1. The bug occurs in a trusted driver firmware loading path and affects MMIO/DPRAM writes.
* Reliable crash or strong DoS concern: +1. Truncated records can cause out-of-bounds reads, and invalid DPRAM writes can plausibly fault, corrupt device state, or break the device.
* Requires admin/root in typical deployments: -2. Firmware installation and driver firmware loading are normally root-controlled.
* Rare hardware-only condition: -1. This requires affected Softing CAN hardware and the relevant driver path.

Paranoid additions or changes:

* Generic memory corruption, strong enough for review: +2 instead of only constrained +1. The patch fixes both source OOB reads and destination OOB writes with attacker-influenced firmware record fields.
* Confidentiality impact plausible: +1. The parser can read beyond the firmware blob, though no direct disclosure path is shown.
* Integrity impact plausible: +1. Out-of-bounds writes to mapped DPRAM/MMIO can corrupt device state or adjacent mapped device space.
* Reduced privilege interpretation: penalty reduced. In environments with delegated firmware or device-management workflows, PR may be closer to PR:L than PR:H.

## 3. Reachability analysis

The realistic trigger is local and firmware-mediated. An attacker must influence the firmware image consumed by the Softing CAN driver or the firmware loading path. In normal deployments this is administrator controlled, so the conservative interpretation treats it as privileged local access.

This is not network reachable by normal CAN traffic. It is not a packet receive path. Containers and namespaces usually do not help unless the container or service is delegated device or firmware management capabilities. The path is also hardware dependent, requiring affected Softing CAN devices.

Call-site confidence: high. The provided patch includes the parser and both firmware loading call sites, including memcpy_toio and memcpy_fromio use of the parsed address and length.

## 4. Severity interpretation

This is stronger than an ordinary validation cleanup because the patch fixes concrete OOB source reads and OOB destination writes. However, practical exploitation is constrained by firmware control requirements and rare hardware dependency. The conservative result behaves like a borderline Moderate issue.

The paranoid result is Actionable Moderate because firmware-controlled length and address fields reach a trusted driver MMIO/DPRAM write path. It does not reach Strong Important on the main score without evidence of attacker-controlled kernel object corruption, privilege escalation, or a realistic non-admin trigger.

## 5. One-sentence report phrase

A malformed Softing CAN firmware image can make the firmware parser read beyond the firmware blob and use attacker influenced record addresses and lengths for out-of-bounds DPRAM/MMIO writes, causing at least local DoS and possible device state corruption.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.

Reason: the bug includes concrete OOB read and OOB write conditions in a firmware-fed trusted driver path, and the practical severity depends heavily on whether firmware loading can be influenced by reduced-privilege local users or device-management services.

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UPSTREAM PATCH SUMMARY
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Patch: can: softing: fw_parse(): validate firmware record spans
Commit: f6d9a6a9512430b395a1940d7b216394fd02d30b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6d9a6a9512430b395a1940d7b216394fd02d30b

Commit description:

fw_parse() reads a fixed record header, a firmware-provided payload,
and a trailing checksum without knowing the end of the firmware blob. A
truncated record can therefore make those reads exceed the blob.

The same record also supplies addresses and lengths for writes into
DPRAM. The generic loader uses wrap-prone mixed signed arithmetic for its
bounds check, while the application loader does not bound the staging
copy at all.

Pass the firmware end to the parser and validate the full source record.
Use a signed wide offset for generic DPRAM records and validate the
application staging span against the mapped DPRAM before copying.

Fixes: 03fd3cf ("can: add driver for Softing card")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Link: https://patch.msgid.link/20260722044347.2708-1-pengpeng@iscas.ac.cn
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/softing/softing_fw.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=f6d9a6a9512430b395a1940d7b216394fd02d30b

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

The original Linux kernel CVE announcement for CVE-2026-80706 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80706

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:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 3
  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: NO
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).