[CVE-2026-80813][MODERATE 7.0] nvmet: fix NULL pointer dereference in nvmet_execute_identify_nslist()

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

CVE: CVE-2026-80813
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: nvmet: fix NULL pointer dereference in nvmet_execute_identify_nslist()
Commit: 61dc1a37e04d4003a19095f54883358330034a39
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61dc1a37e04d4003a19095f54883358330034a39
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80813
Analysis date: Fri, 04 Sep 2026 14:24:19 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A remote NVMe host with access to the target endpoint can trigger a NULL pointer dereference in nvmet_execute_identify_nslist through an Identify CNS 07h command, causing a kernel crash and denial of service without evidence of privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-80813 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80813

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-80813	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80813 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';**CWE-476;*CWE-20;CWE-754;BEST CVSS score: '6.5';DESCR 'A NULL pointer dereference in the NVMe target Identify namespace list path occurs because nvmet_execute_identify_nslist can use req ns csi even though this handler does not initialize req ns. A remote NVMe host can trigger this with an Identify command using CNS 07h for Active Namespace ID List for a specific I/O Command Set when an enabled namespace with a larger NSID is present. For the CVSS the PR:N is used because the attacker does not need local privileges on the target, only reachability to the exposed NVMe target endpoint. The issue is network reachable in NVMe over Fabrics deployments, but it is best modeled as AV:A because NVMe targets are usually deployed on isolated storage or data center networks rather than the public Internet. Impact is denial of service via kernel oops or crash. No direct evidence of information disclosure or privilege escalation is supported by the shown code path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	DANGER NULLPTR SIMPLEFIX NVME LINUS TEST  KPANIC INCREASED_TO_MODERATE7_FROM_MODERATE_BASED_ON_GUESSCVSS	YES	NO	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

* Remote reachable / network-triggerable: +2
  The affected code is in the NVMe target command handling path and can be reached by a remote NVMe host that can connect to the exposed target endpoint.

* Reliable kernel crash / strong DoS: +1
  The bug is a direct NULL pointer dereference of req->ns->csi when req->ns is always NULL in this handler. The described condition leads to an oops or crash.

* Important filesystem/storage path: +1
  The issue affects NVMe target admin command handling, which is a storage control path and can impact availability of a storage server.

* Availability impact realistic: +1 in paranoid score only
  Once the NVMe target is reachable and an enabled namespace with a larger NSID exists, the trigger appears straightforward and can cause a kernel crash. This makes the DoS operationally meaningful.

No memory corruption, UAF, OOB write, arbitrary write, page-cache corruption, or privilege escalation primitive is shown. This is best treated as NULL dereference DoS, not LPE.

## 3. Reachability analysis

A remote NVMe host can trigger the bug by issuing an Identify command with CNS 07h when match_css is set and a suitable enabled namespace exists. The attacker does not need local code execution on the target host, only protocol reachability to the NVMe target endpoint.

This is network reachable in NVMe over Fabrics deployments, but the exposure is usually adjacent or internal rather than Internet-wide. NVMe/TCP and similar targets are typically deployed in storage or data-center networks. Containers and namespaces do not significantly reduce the requirement unless they provide access to the storage network or target endpoint.

The path is not enabled on ordinary systems by default. It requires an NVMe target configuration with exposed namespaces.

## 4. Severity interpretation

This behaves like an actionable Moderate issue rather than ordinary Low because it is remotely reachable from a storage client and can crash the kernel. It does not reach Important based on the supplied patch because the primitive is a NULL pointer dereference only.

Theoretical impact beyond DoS is not supported. There is no evidence of attacker-controlled reclaim, stale object reuse, writable corruption, type confusion, information disclosure, or privilege escalation.

## 5. One-sentence report phrase

A remote NVMe host with access to the target endpoint can trigger a NULL pointer dereference in nvmet_execute_identify_nslist through an Identify CNS 07h command, causing a kernel crash and denial of service without evidence of privilege escalation.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.

Reason: the bug is network reachable in NVMe target deployments and can cause a reliable kernel crash, even though the demonstrated primitive is only NULL pointer dereference DoS.

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

Patch: nvmet: fix NULL pointer dereference in nvmet_execute_identify_nslist()
Commit: 61dc1a37e04d4003a19095f54883358330034a39
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61dc1a37e04d4003a19095f54883358330034a39

Commit description:

When a host issues an Identify command with CNS 07h (Active Namespace ID
List for a specific I/O Command Set), nvmet_execute_identify_nslist() is
called with match_css set. The command-set filter dereferences req->ns,
but this handler never calls nvmet_req_find_ns(), so req->ns is always
NULL (nvmet_req_init() resets it to NULL). As soon as an enabled
namespace with an NSID greater than the requested value exists,
req->ns->csi dereferences a NULL pointer and oopses.

Besides the crash, the comparison is logically wrong: to filter the list
by command set it must test the command set of the namespace being
iterated, not a single fixed value. Use the loop variable ns->csi.

Fixes: 61c9967 ("nvmet: implement active command set ns list")
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/nvme/target/admin-cmd.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=61dc1a37e04d4003a19095f54883358330034a39

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

The original Linux kernel CVE announcement for CVE-2026-80813 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80813

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:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 6.5

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: 4
  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: YES
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).