[CVE-2026-97484][LOW] usbip: vhci_hcd: fix NULL deref in status_show_vhci [ Upstream

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

CVE: CVE-2026-97484
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: usbip: vhci_hcd: fix NULL deref in status_show_vhci [ Upstream
Commit: 046a94fdb02eb1df86c8fa4614104ff801ba3ab7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=046a94fdb02eb1df86c8fa4614104ff801ba3ab7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97484
Analysis date: Thu, 24 Sep 2026 14:49:46 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97484 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97484

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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

CVE-2026-97484	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97484 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-252;CWE-754;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in the USBIP VHCI sysfs status path can occur after a VHCI host controller probe fails and platform_get_drvdata returns NULL. Reading the affected status entry can pass the NULL value to hcd_to_vhci_hcd and later dereference an invalid pointer, resulting in a kernel oops or possible panic and local denial of service. For the CVSS the PR:L value is used because a local process must read the relevant sysfs entry, although creating the failed probe state may require additional system conditions or administrative actions. The issue is not network reachable through USBIP traffic alone. Impact is limited to availability because the patch indicates a NULL dereference and does not provide evidence of a use after free, out of bounds access, information disclosure, arbitrary write, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	NULLPTR USB ERRORPATH IMPROVEONLY LINUS 	NO	NO	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash / strong DoS. A failed VHCI probe can leave platform driver data unset. A subsequent status_show_vhci access converts NULL through hcd_to_vhci_hcd and dereferences the resulting invalid offset pointer. This can produce a kernel Oops and may panic systems configured with panic_on_oops.
* No UAF signal. No object is freed and later accessed. The bug is a NULL-derived invalid pointer dereference.
* No memory corruption signal. The patch does not establish an out of bounds access, write, refcount mutation, double release, stale lifetime operation, or controlled object replacement.
* No remote reachability signal. USBIP network traffic does not directly enter the affected sysfs read path.
* No local unprivileged trigger bonus. Reading sysfs may be available to ordinary users, but the complete trigger also requires an existing failed VHCI probe. The supplied material does not establish whether an unprivileged actor can cause that failed probe state.
* No privilege penalty. Host-admin-equivalent privilege may be needed to create or configure VHCI devices or induce the prerequisite condition, but this is not positively established for the complete path.
* No rare subsystem penalty. USBIP VHCI is optional, but optional subsystem status alone is not a justified negative signal.
* No confidentiality or integrity points. There is no readback, disclosure, write primitive, authorization bypass, or protected-resource access.
* No additional Availability point. The only demonstrated impact is the same kernel fault already counted as strong DoS.

3. Reachability analysis

The immediate vulnerable operation is a local read of the USBIP VHCI sysfs status entry. The vulnerable state exists only if a VHCI host-controller probe previously failed, for example because USB bus numbers were exhausted, leaving platform_get_drvdata returning NULL.

The supplied patch does not establish who can create a VHCI platform device, cause its probe to fail, or retain the failed device state. A host administrator, a privileged USBIP setup process, or an environmental resource-exhaustion condition may be involved. Therefore HostAdminRequired is UNKNOWN rather than YES or NO.

No namespace-scoped complete trigger is established. USBIP and VHCI may interact with namespaces in some deployments, but the evidence does not show that all required stages, including failed probe creation and access to the affected sysfs attribute, are available to an attacker inside an attacker-controlled namespace.

No special physical hardware, race, firmware control, or network packet sequence is required by the demonstrated dereference. The material prerequisite is the failed VHCI probe state.

4. Primitive and severity interpretation

The exact primitive is a NULL pointer dereference caused by missing validation of the hcd value returned by platform_get_drvdata. Passing NULL to hcd_to_vhci_hcd yields a non-NULL offset pointer, and dereferencing vhci_hcd then faults.

This is not a lifetime bug. There is no RealUAF, no active structured stale object, no post-free access, no repeated release, no refcount mutation, and no controlled reclaim or object substitution. The invalid pointer is derived deterministically from NULL and the demonstrated consequence is an immediate invalid dereference.

The correct classification is CLASS_C because the evidence establishes crash or DoS behavior without an independently useful corruption primitive. A privilege-escalation scenario is not supported by the patch. ImportantCandidate is NO because there is no meaningful unresolved exploitation leverage beyond the kernel fault. AutoDowngradeAllowed is YES because this is a constrained NULL-dereference DoS issue, subject to confirming deployment exposure and sysfs permissions.

Operationally, this is a low-priority local availability issue. It can be more operationally relevant on systems that use USBIP VHCI and can enter failed-probe states, especially if panic_on_oops is enabled.

5. One-sentence report phrase

A failed USBIP VHCI probe can leave platform driver data unset, and reading the affected local sysfs status entry can dereference a NULL-derived pointer and cause a kernel Oops or denial of service.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether the affected VHCI status sysfs attribute is readable by untrusted users and whether a below-host-admin actor can create or preserve a failed VHCI probe state in the evaluated deployment.

7. Call-site confidence

Call-site confidence: medium

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

Patch: usbip: vhci_hcd: fix NULL deref in status_show_vhci [ Upstream
Commit: 046a94fdb02eb1df86c8fa4614104ff801ba3ab7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=046a94fdb02eb1df86c8fa4614104ff801ba3ab7

Changed files:
  drivers/usb/usbip/vhci_sysfs.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=046a94fdb02eb1df86c8fa4614104ff801ba3ab7

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

The original Linux kernel CVE announcement for CVE-2026-97484 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97484

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:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: unknown
  Paranoid ActionableScore: 1

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).