* [CVE-2026-98056][MODERATE REGULAR] nvme: remove stale namespaces by NSID range during scan [ Upstream
@ 2026-09-25 15:48 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-25 15:48 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98056
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: nvme: remove stale namespaces by NSID range during scan [ Upstream
Commit: c84ad7407fb16b92d9b7a649cc304a9cf3757897
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c84ad7407fb16b92d9b7a649cc304a9cf3757897
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98056
Analysis date: Fri, 25 Sep 2026 11:48:21 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98056 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98056
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-2026-98056 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98056 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-400;*CWE-835;CWE-407;BEST CVSS score: '6.5';DESCR 'An NVMe controller can report a sparse namespace identifier list that causes nvme_scan_ns_list to process every missing NSID in a large numeric gap. Because NSIDs are 32 bit values, a single sparse gap can result in billions of stale namespace lookup and removal attempts even when few or no namespaces exist in that range. This can cause excessive CPU consumption and a soft lockup in the nvme_scan_work workqueue, resulting in denial of service on the host. For the CVSS the PR:N is used because a remote attacker controlling a reachable NVMe controller does not need local code execution on the host. The attack is adjacent network reachable through an NVMe over Fabrics storage path and normally requires access to the storage network or control of a connected NVMe device. Confidentiality and integrity impact are not supported because the patch indicates an iteration complexity problem and no memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) YES DEADLOCK DANGER NVME HARDWARE LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 3
* Conservative score: 3
* Raw paranoid score: 3
* Paranoid score: 3
* Final recommended bucket: **Borderline / manual review recommended**::
No floor or cap was applied.
2. Signal breakdown
* +2 Remote reachable / directly network-triggerable. A malicious or compromised reachable NVMe over Fabrics controller can return a sparse NSID list during namespace scanning. The attacker needs access to the storage-network path or control of an already connected NVMe controller, but does not need local code execution on the host.
* +1 Reliable kernel DoS. The commit documents a CPU soft lockup in `nvme_scan_work` after billions of namespace ID gap iterations. This can stall a CPU in the NVMe workqueue and degrade host availability.
Important non-awarded signals:
* +0 Memory corruption. No UAF, stale dereference, invalid free, refcount mutation, OOB access, or write primitive is established.
* +0 Confidentiality and integrity. The bug performs excessive valid namespace lookup and removal checks. No disclosure or unauthorized modification primitive is shown.
* +0 Additional availability. The soft lockup and CPU exhaustion are the same demonstrated DoS consequence and are not counted twice.
* +0 Broad/default subsystem exposure. NVMe is broadly deployed, but the vulnerable namespace-list scanning path requires an NVMe controller and is not proven to be broadly exercised in all deployments.
* No race/timing penalty. This is deterministic algorithmic complexity from attacker-controlled NSID gaps, not a narrow timing race.
* No niche or hardware penalty. The flaw can affect NVMe over Fabrics controllers and is not restricted by the supplied evidence to rare physical hardware.
3. Reachability analysis
A malicious NVMe controller can report a namespace list with very large gaps between 32-bit NSID values. The vulnerable host scan path iterates over every missing numerical NSID in such a gap, even if no namespace exists there.
The practical remote attacker model is an attacker controlling an NVMe over Fabrics target, a compromised target, or an attacker able to alter storage-controller responses on a reachable storage network. An arbitrary Internet peer cannot normally reach this path because the host must already be connected to, or configured to use, the malicious NVMe controller.
Host-admin-equivalent privilege is not required on the affected host once the attacker controls the reachable controller response. Therefore `HostAdminRequired=NO`. Namespace-scoped privilege is not relevant to the complete trigger path and remains `UNKNOWN`.
No special kernel configuration, local namespace capability, local ioctl access, or race condition is established as necessary for the remote-controller scenario. A prior host configuration connecting to the NVMe target is operationally required, but this is normal deployment setup rather than a privilege requirement for the attacker on the victim host.
4. Primitive and severity interpretation
The exact primitive is an algorithmic-complexity and excessive-iteration DoS. `nvme_scan_ns_list()` previously invoked namespace removal once for every numeric NSID in a gap. Since NSIDs are 32-bit values, a sparse response can force billions of loop iterations and repeated `nvme_find_get_ns()` calls.
This is neither an active structured-object lifetime violation nor fixed stale storage. There is no UAF, no second release or refcount mutation, no ownership violation, and no stale-object reuse. The patch changes removal from per-NSID iteration to a bounded walk over namespaces actually present in the sorted `ctrl->namespaces` list.
The demonstrated consequence is CPU soft lockup and host-side denial of service. A kernel panic is not directly shown, although prolonged CPU occupation and blocked namespace management are plausible. Privilege escalation, kernel memory corruption, confidentiality impact, and integrity impact are speculative and unsupported.
`PrimitiveClass=NONE` is appropriate because no meaningful corruption, lifetime, authorization, or ownership primitive is established. `ImportantCandidate=NO` because this is a resource-consumption DoS without a demonstrated cross-boundary bypass, corruption primitive, or persistent isolation failure. `AutoDowngradeAllowed=YES` is appropriate from the primitive perspective, although manual review is recommended to determine whether the affected environment exposes NVMe over Fabrics controllers to untrusted storage-network actors.
Likely operational severity is an actionable network-adjacent DoS for storage environments, but not an Important-class kernel-corruption issue.
5. One-sentence report phrase
A malicious reachable NVMe controller can report a sparse NSID list that causes the host namespace scan to perform billions of unnecessary iterations, resulting in CPU soft lockup and denial of service.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Review whether the affected host uses NVMe over Fabrics and whether an untrusted or compromised controller can provide namespace-list responses over the reachable storage network.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: nvme: remove stale namespaces by NSID range during scan [ Upstream
Commit: c84ad7407fb16b92d9b7a649cc304a9cf3757897
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c84ad7407fb16b92d9b7a649cc304a9cf3757897
Changed files:
drivers/nvme/host/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=c84ad7407fb16b92d9b7a649cc304a9cf3757897
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98056 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98056
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: unknown
Paranoid ActionableScore: 3
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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