[CVE-2026-68344][MODERATE 7.0] usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect [ Upstream

[CVE-2026-68344][MODERATE 7.0] usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68344
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect [ Upstream
Commit: c035b1198906dd5bd3df9a3045b59254bad1ea7a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c035b1198906dd5bd3df9a3045b59254bad1ea7a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68344
Analysis date: Mon, 10 Aug 2026 17:50:02 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum**:: Actionable Moderate with manual review. Physical-only reachability prevents treating it as high-end Important by default, but the bug is real type confusion with slab out-of-bounds access in kernel USB disconnect handling.
Manual review required: YES

Summary:
A crafted USB ueagle ATM device can make probe and disconnect disagree about the stored interface object type, causing `struct completion` to be treated as `struct usbatm_data` and leading to slab out-of-bounds access and kernel crash during disconnect.

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

The original Linux kernel CVE announcement for CVE-2026-68344 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68344

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.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-68344	MODERATE	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-843;CWE-125;*CWE-787;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.8';DESCR 'A crafted USB ATM ueagle device can advertise inconsistent pre firmware and interface count information so uea_probe and uea_disconnect classify the same interface differently. This causes interface data for a small completion object to be treated as struct usbatm_data during disconnect, leading to type confusion and slab out-of-bounds access when usbatm_usb_disconnect reaches the serialize mutex. For the CVSS the PR:N is used because the attacker does not need a local account on the victim system, but practical triggering requires physical USB access or getting the device attached. The issue is not network reachable. Impact is at least denial of service via kernel crash. In the paranoid case, the out-of-bounds access and wrong object type make limited or full confidentiality and integrity impact plausible enough for manual review sensitivity.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-68344 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: e2674dfbed8a30d57e2bc872c4bfa6c3eec918bf YES  NO NO unknown 	MAYBE	READ KASAN OOB USB INIT HARDWARE LINUS SYZBOT  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: Actionable Moderate with manual review. Physical-only reachability prevents treating it as high-end Important by default, but the bug is real type confusion with slab out-of-bounds access in kernel USB disconnect handling.

## 2. Signal breakdown

Conservative signals:

* Generic memory corruption / reliable type confusion: +2
  `uea_probe()` stores either `struct completion` or `struct usbatm_data`, while `uea_disconnect()` classifies the object using a different criterion. A crafted descriptor can make `struct completion` be interpreted as `struct usbatm_data`.

* Weak LPE concern: +1
  The primitive is invalid struct interpretation with an out-of-bounds access inside a mutex path. No arbitrary write or controlled reclaim is shown, but the object confusion is strong enough to require review.

* Reliable kernel crash / strong DoS: +1
  KASAN reports slab-out-of-bounds in `__mutex_lock()` through `usbatm_usb_disconnect()`.

* Privileged kernel/device-management memory corruption path: +1
  The corruption occurs in USB driver probe/disconnect handling based on device supplied descriptors.

* Physical-only condition: -2
  Triggering requires a crafted USB device or equivalent USB-device emulation attached to the victim. It is not network reachable.

Conservative total: 3

Paranoid additions:

* Confidentiality impact plausible: +1
  Type confusion and OOB read make limited disclosure theoretically plausible, although not demonstrated.

* Integrity impact plausible: +1
  Misinterpreting one kernel object as another may reach corruption sinks in non-KASAN builds, but no controlled write primitive is shown.

Paranoid total: 5

Call-site confidence: high. The commit includes the exact mismatched probe/disconnect behavior and a KASAN stack trace showing the failing call path.

## 3. Reachability analysis

The attacker does not need a local user account on the victim, so PR is effectively none in CVSS terms. Practical triggering requires physical access to a USB port, a malicious USB device, or a USB device emulation environment. Namespaces and containers do not materially lower or raise the requirement because the vulnerable path is kernel USB enumeration and disconnect handling, not a namespace-local syscall API.

The path is not remotely network reachable. Exposure depends on whether the `ueagle-atm` USB ATM driver is built, loadable, and matched by the crafted USB identifiers. The subsystem is legacy and device-specific, but once the driver is present the trigger path is ordinary USB probe and disconnect behavior.

## 4. Severity interpretation

This is stronger than an ordinary Moderate crash because it is a concrete type confusion between two different kernel object layouts, followed by slab out-of-bounds access. Realistic impact is most clearly local physical DoS via kernel crash. The patch does not show attacker-controlled reclaim, arbitrary write, callback control, or a stable privilege-escalation primitive, so conservative scoring should not treat it as a proven LPE.

Paranoid handling is justified because kernel object type confusion in a driver disconnect path can be underestimated, especially when the observed failure is an OOB access through a synchronization object. It should not be auto-closed as a low-risk cleanup.

## 5. One-sentence report phrase

A crafted USB ueagle ATM device can make probe and disconnect disagree about the stored interface object type, causing `struct completion` to be treated as `struct usbatm_data` and leading to slab out-of-bounds access and kernel crash during disconnect.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is physical-only and not network reachable, but it is a real object type confusion with KASAN-confirmed slab out-of-bounds access in kernel USB driver code, so manual review is needed before downgrading it to ordinary Moderate.

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

Patch: usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect [ Upstream
Commit: c035b1198906dd5bd3df9a3045b59254bad1ea7a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c035b1198906dd5bd3df9a3045b59254bad1ea7a

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=c035b1198906dd5bd3df9a3045b59254bad1ea7a

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

The original Linux kernel CVE announcement for CVE-2026-68344 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68344

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: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: 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).