From: AL-KERNEL <[email protected]>
To: [email protected]
Subject: [CVE-2026-46105][IMPORTANT] scsi: mpt3sas: Limit NVMe request size to 2 MiB
Date: Thu, 28 May 2026 19:18:12 -0400 [thread overview]
Message-ID: <[email protected]> (raw)
CVE: CVE-2026-46105
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: scsi: mpt3sas: Limit NVMe request size to 2 MiB
Commit: 45dcc815fc5539e88154315f36cbcb11d3a52fc2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45dcc815fc5539e88154315f36cbcb11d3a52fc2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46105
Analysis date: Thu, 28 May 2026 19:18:12 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES
Summary:
A local user able to generate large I/O on an affected mpt3sas NVMe-backed device may trigger oversized PRP list construction beyond the fixed 4 KiB driver buffer, causing at least a kernel oops and warranting manual review for constrained memory corruption risk.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-46105 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46105
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-46105 IMPORTANT CHECK 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-787;CWE-119;*CWE-20;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.8';DESCR 'mpt3sas can accept an NVMe MDTS value larger than the PRP list capacity that the driver actually allocates. The driver uses a fixed 4 KiB PRP list buffer with room for at most 512 entries, so I/O larger than 2 MiB can exceed the supported request description and may lead to a kernel oops. For the CVSS the PR:L is selected for the paranoid score because a local user with access to files or block I/O on an affected device may be able to generate large I/O without full administrator privileges. The issue is not network reachable and requires an affected mpt3sas HBA with NVMe devices and a request size path that can exceed 2 MiB. Impact is at least local denial of service via kernel crash. In the worst case the fixed buffer and oversized PRP list context make memory corruption plausible enough to justify manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) MAYBE SIMPLEFIX HARDWARE KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=7
ActionableScoreLower=5
## 1. ActionableScore
* Conservative score: **5**
* Paranoid score: **7**
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::
## 2. Signal breakdown
Conservative signals:
* **Local unprivileged trigger: +1**
A local user with access to files or block I/O on an affected device may be able to generate large I/O without full administrator privileges.
* **Constrained kernel buffer overwrite / weak corruption candidate: +1**
The driver has a fixed 4 KiB PRP list buffer with capacity for 512 entries. Oversized I/O beyond 2 MiB can exceed the request description capacity. Payload and overwrite target control are not clearly demonstrated, so this is not scored as strong arbitrary corruption.
* **Reliable kernel crash / strong DoS: +1**
The commit explicitly says oversized I/O may lead to a kernel oops.
* **Privileged kernel/device-management memory corruption path: +1**
The issue is in a trusted SCSI/NVMe HBA driver path, involving firmware-reported limits and DMA-adjacent request metadata.
* **Important filesystem/storage path: +1**
The bug affects block/storage I/O sizing and request construction.
Paranoid additional signals:
* **Firmware-mediated external influence: +1**
The problematic limit is derived from HBA firmware and NVMe drive MDTS reporting, so malformed or overly large reported capability values influence kernel behavior.
* **Weak LPE concern: +1**
Because the failure mode involves a fixed kernel buffer and oversized PRP list construction, limited memory corruption is plausible enough for manual review, although no arbitrary write or reliable reclaim primitive is shown.
Exposure adjustment:
* **Hardware/configuration dependent: -1 considered but not applied in paranoid score**
The issue requires affected mpt3sas hardware and NVMe devices behind the HBA, but this is a realistic storage deployment class, not a purely artificial configuration.
## 3. Reachability analysis
The bug is **not network reachable**. Triggering requires an affected mpt3sas HBA exposing NVMe devices and an I/O path capable of issuing requests larger than the driver-supported 2 MiB PRP list limit.
In typical deployments, a local unprivileged user may be able to trigger large filesystem or block-backed I/O if they have access to storage on the affected device. Direct raw block access may require privileges, but ordinary file I/O can still reach the block layer depending on filesystem, mount, and workload behavior.
Namespaces and containers may matter if a containerized or delegated workload can generate I/O to storage backed by the affected controller. This does not require CAP_SYS_ADMIN in the strongest practical interpretation, so PR:L is reasonable for paranoid triage.
## 4. Severity interpretation
This is more than an ordinary low-risk DoS because the crash is tied to an oversized request against a fixed kernel PRP list buffer in a privileged storage driver path. The conservative interpretation is **Actionable Moderate**: local DoS through kernel oops.
The paranoid interpretation is a **Strong Important candidate** for manual review because fixed kernel buffer capacity versus oversized I/O request construction can be a memory corruption pattern. However, the patch does not demonstrate attacker-controlled target selection, arbitrary payload control, UAF reclaim, or a reliable privilege escalation primitive, so it should not be treated as proven LPE without further analysis.
## 5. One-sentence report phrase
A local user able to generate large I/O on an affected mpt3sas NVMe-backed device may trigger oversized PRP list construction beyond the fixed 4 KiB driver buffer, causing at least a kernel oops and warranting manual review for constrained memory corruption risk.
## 6. Manual review recommendation
**MANUAL CHECK REQUIRED**
The bug involves a fixed kernel buffer in a privileged storage driver and oversized request construction. The demonstrated impact is DoS, but the corruption-adjacent PRP list context is strong enough that it should not be auto-closed without manual inspection.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: scsi: mpt3sas: Limit NVMe request size to 2 MiB
Commit: 45dcc815fc5539e88154315f36cbcb11d3a52fc2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45dcc815fc5539e88154315f36cbcb11d3a52fc2
Commit description:
The HBA firmware reports NVMe MDTS values based on the underlying drive
capability. However, because the driver allocates a fixed 4K buffer for
the PRP list, accommodating at most 512 entries, the driver supports a
maximum I/O transfer size of 2 MiB.
Limit max_hw_sectors to the smaller of the reported MDTS and the 2 MiB
driver limit to prevent issuing oversized I/O that may lead to a kernel
oops.
Cc: [email protected]
Fixes: 9b8b848 ("block: Increase BLK_DEF_MAX_SECTORS_CAP")
Reported-by: Mira Limbeck <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9b8b84879d4a
Suggested-by: Keith Busch <[email protected]>
Signed-off-by: Ranjan Kumar <[email protected]>
Tested-by: Mira Limbeck <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
kernel/git/torvalds/linux.git
drivers/scsi/mpt3sas/mpt3sas_scsih.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=45dcc815fc5539e88154315f36cbcb11d3a52fc2
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-46105 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46105
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:L/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: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: 5
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
reply other threads:[~2026-05-28 23:18 UTC|newest]
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