[CVE-2026-64341][MODERATE 7.0] USB: iowarrior: fix use-after-free on disconnect race [ Upstream

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

CVE: CVE-2026-64341
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: USB: iowarrior: fix use-after-free on disconnect race [ Upstream
Commit: 3c0a7b29ebb391d5f50b115e86f842b709195b08
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c0a7b29ebb391d5f50b115e86f842b709195b08
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64341
Analysis date: Sat, 25 Jul 2026 06:19:32 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race between iowarrior release() and disconnect() can free driver data while mutex_unlock() may still access the embedded mutex, causing a local use-after-free and likely kernel crash, with theoretical but unproven privilege-escalation relevance due to the UAF class.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64341 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64341

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-2026-64341	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use-after-free can occur in the USB iowarrior driver when release() races with disconnect() and the driver data is freed while mutex_unlock() may still access the mutex object. A local attacker with access to the iowarrior device node can potentially trigger the race during device close and disconnect handling, causing a kernel crash. For the CVSS the PR:L is used because reliable triggering requires a local user or process with access to the device interface rather than unauthenticated network access. The issue is not network reachable. Impact is at least a local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to kernel use-after-free memory corruption. Exploitation beyond DoS is not proven from the patch alone but the UAF class makes this suitable for manual security review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	YES	LOCK USB INIT RACE UAF DMAorINTERRUPT HARDWARE KPANIC 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  A local process with access to the iowarrior character device can open and close the device while disconnect handling runs.

* Memory corruption, weak race-UAF primitive: +1
  The patch explicitly fixes a use-after-free, but it is race-dependent and the patch does not show attacker-controlled reclaim, callback control, type confusion, or write-after-free.

* Real lifetime corruption: +1
  The object lifetime was managed incorrectly across open, release, and disconnect. The fix adds kref-based lifetime management.

* Reliable kernel crash / strong DoS: +1
  A UAF in mutex_unlock() can realistically lead to kernel crash or memory safety failure.

* Privileged kernel/device-management lifetime path: +1
  The bug is in USB driver disconnect/release lifetime handling, involving kernel driver objects and URB/device teardown state.

Subtracted signals:

* Hard or unreliable race / special timing required: -1
  Triggering requires a release() vs disconnect() race and timing around mutex_unlock() object lifetime.

Paranoid interpretation:

* Paranoid score is raised to 5 because this is a real kernel UAF in driver object lifetime management. No strong LPE primitive is demonstrated, so the score is not raised beyond Actionable Moderate.

## 3. Reachability analysis

The bug is locally reachable by a process that can access the iowarrior device node and race close/release against device disconnect or equivalent unbind/removal behavior. It is not network reachable. Namespace impact is limited because access depends on whether the USB device node is exposed into a container or sandbox. The driver is not a broad default network or filesystem path and requires iowarrior hardware or an exposed emulated/test device, but the affected release/disconnect path is realistic once the device is present.

Call-site confidence: high. The patch includes the relevant open(), release(), probe(), error cleanup, and disconnect() paths.

## 4. Severity interpretation

This is not an ordinary low-risk cleanup because the commit explicitly identifies a use-after-free caused by incorrect object lifetime handling around mutex_unlock(). Realistic demonstrated impact is local DoS via kernel crash. Privilege escalation is only theoretical here because the patch does not show controlled reclaim, stale callback dispatch, type confusion, arbitrary write, or attacker-controlled object replacement. Therefore it fits Actionable Moderate, with Strong Important candidate only for paranoid manual-review triage.

## 5. One-sentence report phrase

A race between iowarrior release() and disconnect() can free driver data while mutex_unlock() may still access the embedded mutex, causing a local use-after-free and likely kernel crash, with theoretical but unproven privilege-escalation relevance due to the UAF class.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

This is a real kernel UAF in device lifetime management. Even though exploitation beyond DoS is not demonstrated, UAF races in driver teardown paths should not be auto-closed without manual review.

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

Patch: USB: iowarrior: fix use-after-free on disconnect race [ Upstream
Commit: 3c0a7b29ebb391d5f50b115e86f842b709195b08
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c0a7b29ebb391d5f50b115e86f842b709195b08

Changed files:
  drivers/usb/misc/iowarrior.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=3c0a7b29ebb391d5f50b115e86f842b709195b08

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

The original Linux kernel CVE announcement for CVE-2026-64341 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64341

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