[CVE-2026-90227][IMPORTANT] nvme/ioctl: check SUBMIT_IO with nvme_cmd_allowed() [ Upstream

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

CVE: CVE-2026-90227
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: nvme/ioctl: check SUBMIT_IO with nvme_cmd_allowed() [ Upstream
Commit: c35cd98eed1a863e8dd51073953563cd8c907f68
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c35cd98eed1a863e8dd51073953563cd8c907f68
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90227
Analysis date: Fri, 18 Sep 2026 00:49:50 -0400
ActionableScore: 7
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-90227 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90227

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: IMPORTANT
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
======================================================================

CVE-2026-90227	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-90227 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-862;CWE-863;CWE-284;BEST CVSS score: '7.8';DESCR 'NVMe SUBMIT_IO ioctl did not apply nvme_cmd_allowed checks, unlike the other NVMe ioctl command paths. A local caller with access to an NVMe namespace or partition file descriptor could issue I/O that should have been rejected, including I/O through a partition device or writes through a read-only file descriptor. For the CVSS the PR:L is selected because a local caller needs access to the NVMe device file or an already opened file descriptor, but full administrator privileges are not necessarily required once that access exists. The issue is not network reachable and is triggered through a local ioctl interface. Impact can include unauthorized storage access, data modification, filesystem corruption, and a plausible local privilege escalation path if protected system data can be modified through the affected block device.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate (with actual score 7)	YES	NVME HARDWARE LINUS  KPANIC INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHERTHAN5	NO	NO	checked

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

ActionableScore=7
ActionableScoreLower=6
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 6
* Conservative score: 6
* Raw paranoid score: 7
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate**::

No floor or cap was applied. The paranoid score is emitted as the final ActionableScore because the patch establishes a real authorization bypass in a storage ioctl path, and a defensible worst case includes unauthorized access to protected storage contents.

2. Signal breakdown

Positive signals:

* +2 Concrete authorization decision bypass: `NVME_IOCTL_SUBMIT_IO` skipped `nvme_cmd_allowed()`, allowing commands that other NVMe ioctl paths reject.
* +1 Local unprivileged trigger: the commit explicitly says unprivileged callers can issue the disallowed I/O.
* +1 Integrity plausible: the bypass permits writes through a read-only file descriptor, which can modify storage contrary to the intended access mode.
* +1 Important storage path: this affects NVMe block device I/O, where unauthorized access can affect filesystem or raw disk contents.
* +1 Practical exploit chain strongly implied: the commit directly identifies meaningful consequences, namely I/O on a partition device and writes through a read-only FD.

Paranoid-only signal:

* +1 Confidentiality plausible: issuing I/O on a partition device may allow access inconsistent with partition or device-node boundaries, depending on deployment and command direction.

Non-awarded signals:

* RealUAF not awarded: no lifetime bug or stale object use is present.
* Memory corruption not awarded: this is an authorization and access-control bypass, not a kernel memory corruption primitive.
* Remote reachability not awarded: the trigger is a local ioctl path, not network traffic.
* Reliable kernel crash not awarded: no kernel panic or crash primitive is established.
* Privileged FD theft not awarded: no downstream pidfd or privileged FD acquisition chain is supplied.
* Demonstrated root LPE not awarded: privilege escalation is plausible through storage modification, but not demonstrated by the supplied evidence.

3. Reachability analysis

The trigger is local through `NVME_IOCTL_SUBMIT_IO` on an NVMe namespace or partition device. The supplied commit message explicitly states that unprivileged callers can issue the affected I/O, so host administrator privilege is not required for the vulnerable operation once the attacker has access to the device file or an already opened file descriptor.

This is not namespace-scoped in the meaningful capability sense. The issue is not about gaining `CAP_NET_ADMIN`, `CAP_SYS_ADMIN`, or a namespace-local capability. It is an ioctl authorization failure in the NVMe host driver.

Prior setup is limited to the system having an NVMe device and an exposed device node or FD reachable by the attacker. No special hardware beyond NVMe is unusual in modern systems. No race or timing condition is required.

4. Primitive and severity interpretation

The exact primitive is an authorization bypass in a storage ioctl path. `NVME_IOCTL_SUBMIT_IO` failed to call `nvme_cmd_allowed()`, so it did not enforce restrictions that apply to other NVMe ioctl command paths.

This is `PrimitiveClass=CLASS_A` because the patch restores a concrete missing authorization decision. The vulnerable path changes behavior from reject disallowed command to allow disallowed command.

The demonstrated consequence is unauthorized storage I/O, including writes through a read-only file descriptor and I/O on partition devices. The speculative but plausible consequence is local privilege escalation if the unauthorized write can modify protected system data, filesystem metadata, boot files, configuration, credentials, or another privileged storage object.

ImportantCandidate is YES because this is a meaningful security-boundary bypass with direct storage integrity impact. AutoDowngradeAllowed is NO because automatically treating this as ordinary Moderate could miss a practical local privilege escalation or protected-data modification scenario.

5. One-sentence report phrase

NVMe SUBMIT_IO failed to enforce nvme_cmd_allowed checks, allowing an unprivileged local caller with access to an affected NVMe device or FD to issue unauthorized storage I/O such as writes through a read-only descriptor, with potential data modification and local privilege escalation impact.

6. Manual review recommendation

MANUAL CHECK REQUIRED

This needs manual review because it is a concrete authorization bypass in a block storage path with direct integrity impact and plausible privilege-escalation consequences depending on device-node permissions and what protected storage can be modified.

7. Call-site confidence

Call-site confidence: high

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

Patch: nvme/ioctl: check SUBMIT_IO with nvme_cmd_allowed() [ Upstream
Commit: c35cd98eed1a863e8dd51073953563cd8c907f68
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c35cd98eed1a863e8dd51073953563cd8c907f68

Changed files:
  drivers/nvme/host/ioctl.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=c35cd98eed1a863e8dd51073953563cd8c907f68

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

The original Linux kernel CVE announcement for CVE-2026-90227 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90227

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: Not available
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 6
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).