[CVE-2026-63906][MODERATE REGULAR] usb: musb: omap2430: Fix use-after-free in omap2430_probe() [ Upstream

[CVE-2026-63906][MODERATE REGULAR] usb: musb: omap2430: Fix use-after-free in omap2430_probe() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-63906
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: usb: musb: omap2430: Fix use-after-free in omap2430_probe() [ Upstream
Commit: 632fd888fe33083927e29ef651ac1aba345edd9e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=632fd888fe33083927e29ef651ac1aba345edd9e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63906
Analysis date: Sun, 19 Jul 2026 23:12:10 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A use-after-free in the OMAP2430 MUSB probe path can occur when `of_node_put(np)` drops the device-tree node reference before the last access to `np`, but practical triggering normally requires privileged local device-management control and the likely impact is kernel crash or probe-time DoS.

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

The original Linux kernel CVE announcement for CVE-2026-63906 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63906

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.

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

CVE-2026-63906	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:H/UI:N/S:U/C:H/I:H/A:H';*CWE-416;*CWE-672;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.4';DESCR 'A use after free can occur in the usb musb omap2430 probe path because of_node_put(np) may drop the last reference to the device tree node before the final access to np. This is a local platform driver initialization issue and is not network reachable. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over driver probe, bind, unbind, module loading, or device tree based platform device setup. Impact is at least a local denial of service via kernel crash. In the paranoid interpretation, limited or high confidentiality and integrity impact remains possible because the bug class is kernel use after free, but practical exploitation beyond DoS is constrained by the probe time trigger and hardware specific exposure.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4)  SKIP CVE-2026-63906 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	USB ERRORPATH UAF HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**

## 2. Signal breakdown

Conservative signals:

* Generic memory corruption, constrained UAF: +1
  The patch explicitly fixes a use-after-free of a `struct device_node`, but the stale access is in a driver probe path and no attacker-controlled reclaim, overwrite, callback, or object replacement primitive is shown.

* Real lifetime corruption: +1
  `of_node_put(np)` can drop the last reference before the final use of `np`.

* Privileged kernel/device-management lifetime path: +1
  The bug is in USB MUSB OMAP2430 platform-driver initialization and involves kernel device-tree object lifetime handling.

* Requires admin/root/device-management control in typical deployments: -2
  Reliable triggering normally requires control over driver probe, bind/unbind, module/device setup, or device-tree/platform-device configuration.

* Rare AND difficult-to-reach subsystem/configuration: -1
  This is hardware/platform specific and not a broad default kernel path.

* Availability impact realistic: +1
  If the freed node is actually reused or invalidated, the most realistic impact is kernel crash or probe failure.

Paranoid additional interpretation:

* Kernel UAF manual-review uplift: +1
  Because the patch explicitly fixes a kernel UAF, a cautious triage should not auto-close it even though exploitation beyond DoS is not demonstrated.

## 3. Reachability analysis

The affected path is local and occurs during `omap2430_probe()` for the OMAP2430 MUSB USB platform driver. It is not network reachable. Typical triggering requires privileged control over platform device probing, driver binding, module loading, or device-tree related setup. Ordinary unprivileged users normally cannot create or manipulate this probe path.

Namespaces and containers do not usually make this reachable unless a container or delegated environment has meaningful device-management privileges over the affected platform device, which is uncommon. The vulnerable subsystem is hardware-specific and not a broad default interface on general-purpose systems.

Call-site confidence: medium. The changed code and function context are visible enough to identify the lifetime bug, but the full later uses of `np` and practical refcount drop conditions are not fully shown in the provided snippet.

## 4. Severity interpretation

This behaves more like a borderline Moderate issue requiring manual review than an Important-class vulnerability. The theoretical concern is real kernel UAF, but the practical exploitation evidence is weak because the trigger is probe-time, privileged, hardware-specific, and no reclaim or attacker-controlled reuse primitive is shown. Realistic impact is most likely local DoS or driver initialization instability.

## 5. One-sentence report phrase

A use-after-free in the OMAP2430 MUSB probe path can occur when `of_node_put(np)` drops the device-tree node reference before the last access to `np`, but practical triggering normally requires privileged local device-management control and the likely impact is kernel crash or probe-time DoS.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because this is an explicit kernel UAF in a privileged device-management path, but it does not currently show enough attacker control to classify as a strong Important candidate.

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

Patch: usb: musb: omap2430: Fix use-after-free in omap2430_probe() [ Upstream
Commit: 632fd888fe33083927e29ef651ac1aba345edd9e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=632fd888fe33083927e29ef651ac1aba345edd9e

Changed files:
  drivers/usb/musb/omap2430.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=632fd888fe33083927e29ef651ac1aba345edd9e

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

The original Linux kernel CVE announcement for CVE-2026-63906 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63906

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:H/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 4

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).