[CVE-2026-68456][MODERATE REGULAR] usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect() [ Upstream

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

CVE: CVE-2026-68456
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect() [ Upstream
Commit: d85f19aaef42a03e3e4765d659c761c8750a7f23
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d85f19aaef42a03e3e4765d659c761c8750a7f23
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68456
Analysis date: Sun, 16 Aug 2026 03:42:26 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended, not Strong Important
Manual review required: YES

Summary:
A ueagle-atm async firmware loading race can let firmware sysfs fallback run concurrently with USB disconnect, potentially hitting kernfs or device lifetime errors and causing a kernel DoS when a matching USB device is removed during firmware load.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68456 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68456

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-2026-68456	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-362;*CWE-416;CWE-667;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.3';DESCR 'ueagle-atm starts asynchronous firmware loading from probe but did not wait for that work in disconnect. If the USB device is unplugged while firmware loading falls back to sysfs, the firmware helper can race with device removal and create sysfs objects under a device directory that is being torn down. This can hit kernfs or device lifetime errors and can crash or destabilize the kernel. For the CVSS the PR:N is used because a physical attacker or malicious USB device does not need an account on the target host. The issue is not network reachable and normally requires physical USB access or an equivalent USB emulation setup. Impact is primarily denial of service. In the paranoid score, limited confidentiality or integrity impact is kept possible because the race involves asynchronous teardown and object lifetime handling, but no strong arbitrary write primitive is evident.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended, not Strong Important (with actual score 3)	YES	DANGER USB INIT NOMEMCHK RACE ERRORPATH HARDWARE LINUS TEST SYZBOT 	NO	NO	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 manual review recommended, not Strong Important**

## 2. Signal breakdown

Triggered signals:

* Firmware-mediated external influence: +1
  The issue is reached through asynchronous firmware loading and firmware sysfs fallback while a USB device is being disconnected.

* Real lifetime corruption: +1
  The bug is an async lifetime mismatch. `request_firmware_nowait()` can continue while `.disconnect()` tears down the USB device state.

* Reliable kernel crash / strong DoS: +1
  Multiple syzbot reports show failures in the kernfs/sysfs fallback path during concurrent device removal. The realistic impact is kernel crash or kernel subsystem destabilization.

* Weak/indirect corruption candidate in paranoid score: +1
  The race involves device/kobject/kernfs lifetime handling, but the patch does not show attacker-controlled reclaim, object replacement, callback control, arbitrary write, or a strong UAF primitive.

Negative or limiting signals:

* Hard or unreliable race / special timing required: -1
  Triggering requires a timing window between async firmware fallback and USB disconnect/removal.

* No remote network reachability: +0
  This is not reachable over the network.

* No local unprivileged software-only trigger: +0
  A normal local user cannot reliably trigger this without USB device control, USB gadget/emulation, or physical access.

* No strong LPE primitive: +0
  The patch supports a race/lifetime concern and DoS, but not a demonstrated privilege escalation primitive.

## 3. Reachability analysis

The bug is triggered when a ueagle-atm pre-firmware USB device starts async firmware loading and is disconnected before the firmware path completes. A malicious physical USB device, USB gadget setup, or device emulator can likely influence the timing. Ordinary remote attackers cannot trigger it.

Namespaces and containers do not materially lower the requirement unless the attacker controls USB device attachment or a USB gadget/emulation environment. The affected driver is legacy and device-specific, and the most visible failure path depends on firmware sysfs fallback behavior such as `CONFIG_FW_LOADER_USER_HELPER`.

Call-site confidence: high. The patch shows the async callback context, the new completion object, and the `.disconnect()` wait path.

## 4. Severity interpretation

This behaves like an ordinary to borderline Moderate kernel issue rather than an Important-class vulnerability. The strongest realistic impact is DoS through a race between firmware fallback and device teardown. Theoretical lifetime corruption is plausible because sysfs/kernfs and USB device objects are involved, but there is no evidence of controlled reuse, arbitrary write, type confusion, or privilege escalation.

The paranoid score is kept slightly higher to avoid auto-closing a race involving object lifetime and teardown, but it should not be treated as a strong Important candidate based on the supplied patch.

## 5. One-sentence report phrase

A ueagle-atm async firmware loading race can let firmware sysfs fallback run concurrently with USB disconnect, potentially hitting kernfs or device lifetime errors and causing a kernel DoS when a matching USB device is removed during firmware load.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a race in async device teardown and firmware fallback with possible lifetime implications, and it has multiple syzbot reports. However, current evidence supports DoS and weak lifetime concern only, not a demonstrated LPE primitive.

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

Patch: usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect() [ Upstream
Commit: d85f19aaef42a03e3e4765d659c761c8750a7f23
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d85f19aaef42a03e3e4765d659c761c8750a7f23

Changed files:
  drivers/usb/atm/ueagle-atm.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=d85f19aaef42a03e3e4765d659c761c8750a7f23

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

The original Linux kernel CVE announcement for CVE-2026-68456 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68456

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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.3

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).