[CVE-2026-45911][LOW] usb: cdns3: fix role switching during resume [ Upstream

[CVE-2026-45911][LOW] usb: cdns3: fix role switching during resume [ Upstream

[AL-KERNEL]

CVE: CVE-2026-45911
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: usb: cdns3: fix role switching during resume [ Upstream
Commit: ff02bd303d2d78051771db51119d66c0cf442f47
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ff02bd303d2d78051771db51119d66c0cf442f47
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45911
Analysis date: Wed, 27 May 2026 21:50:52 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A cdns3 USB role-switching bug can call the host resume path before `xhci-hcd` probing completes during system resume, causing a platform-specific NULL pointer dereference and local DoS.

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

The original Linux kernel CVE announcement for CVE-2026-45911 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45911

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.

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

CVE-2026-45911	LOW	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A cdns3 USB role switching bug can call the new host role resume path before the xhci hcd device has completed probing during system resume. If the USB role changes while the controller is suspended, cdns_resume() may start the new role and then incorrectly run its resume callback, leading to a NULL pointer dereference in the host path. For the CVSS the PR:L is used in the paranoid score because some systems allow local users or services to trigger suspend and resume through policy, although reliable triggering often requires privileged power management control or a physical role change. The issue is not network reachable. Impact is denial of service through kernel oops. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) 	MAYBE	OOB NULLPTR USB HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

* Reliable kernel crash / strong DoS: +1
  The patch and trace show a NULL pointer dereference during `cdns_resume()` when the host role resume path runs before `xhci-hcd` probing completes.

* Availability impact realistic: +1
  The realistic impact is kernel oops or local system crash during resume.

* Local trigger via suspend or resume policy: +1 in paranoid scoring
  Some desktop or embedded systems allow local users or services to trigger suspend and resume through policy.

* Requires privileged or physical/platform conditions in typical deployments: -2 conservative
  Reliable triggering usually requires system power-management control and a USB role change while suspended, often tied to platform or physical role-switch state.

* Rare and platform-specific subsystem: -1 conservative
  This affects cdns3 USB controller platforms and a specific role-switching during resume sequence.

* No memory corruption: +0
  The bug is a NULL pointer dereference due to sequencing, not UAF, OOB write, heap corruption, or arbitrary write.

* No privilege escalation or confidentiality impact: +0
  The patch does not support LPE, data disclosure, or integrity impact.

## 3. Reachability analysis

The bug is reachable on affected cdns3 USB controller platforms if the USB role changes while the system is suspended and resume then switches to host mode. Triggering may require local suspend or resume control, physical USB role manipulation, platform policy, or embedded device behavior. Namespaces and containers do not materially affect reachability unless suspend or device role control is exposed to an untrusted workload.

The issue is not network reachable. Realistic exploitation is DoS-only and platform-specific.

## 4. Severity interpretation

This behaves like Low or ordinary Moderate availability impact. It is a real kernel crash path, but it depends on a specific hardware controller, suspend/resume timing, and USB role switching. There is no evidence of memory corruption beyond NULL dereference, no privilege escalation primitive, and no remote trigger.

## 5. One-sentence report phrase

A cdns3 USB role-switching bug can call the host resume path before `xhci-hcd` probing completes during system resume, causing a platform-specific NULL pointer dereference and local DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a platform-specific suspend/resume NULL dereference with DoS-only impact and no supported memory corruption, information disclosure, privilege escalation, or network reachability.

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

Patch: usb: cdns3: fix role switching during resume [ Upstream
Commit: ff02bd303d2d78051771db51119d66c0cf442f47
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ff02bd303d2d78051771db51119d66c0cf442f47

Changed files:
  drivers/usb/cdns3/core.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=ff02bd303d2d78051771db51119d66c0cf442f47

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

The original Linux kernel CVE announcement for CVE-2026-45911 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45911

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 2

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).