* [CVE-2026-93115][LOW] platform/mellanox: mlxbf-pmc: Check ACPI_COMPANION() against NULL [ Upstream
@ 2026-09-18 10:45 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-18 10:45 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93115
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: platform/mellanox: mlxbf-pmc: Check ACPI_COMPANION() against NULL [ Upstream
Commit: 950d8e8375f3ff4787de51b7bdf8dd23a3ad6547
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=950d8e8375f3ff4787de51b7bdf8dd23a3ad6547
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93115
Analysis date: Fri, 18 Sep 2026 06:45:30 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93115 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93115
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-93115 LOW https://www.kernelcve.org/list/?q=CVE-2026-93115 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:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'mlxbf_pmc_probe() can dereference a NULL ACPI companion because ACPI_COMPANION() was used without checking whether the platform device actually has an ACPI companion object. A local attacker who can force-bind platform drivers via device_match_driver_override() can bind mlxbf-pmc to an incompatible device and trigger a NULL pointer dereference in acpi_device_hid(), causing a kernel crash or oops. For the CVSS the PR:L is used only for the paranoid score because some environments may delegate limited device management or driver binding capabilities to a non full administrator. The typical practical requirement is PR:H because sysfs driver binding is normally restricted to root or an equivalent administrator. The issue is not network reachable and the impact is denial of service only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES NULLPTR SIMPLEFIX HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: -1
* Conservative score: 0
* Raw paranoid score: -1
* Paranoid score: 0
* Applied floor/cap: minimum score clamp applied from -1 to 0.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash / strong DoS: force-binding mlxbf-pmc to a platform device without an ACPI companion can make acpi_device_hid() dereference NULL and cause an oops or crash.
* -2 Host-admin-equivalent privilege required: the described trigger is platform driver force-binding through driver_override / bind style device management, which is normally a host sysfs driver-management operation requiring root or equivalent host administrative control.
* +0 Real UAF not awarded: no freed object, stale reference, double release, refcount misuse, RCU lifetime bug, or post-lifetime use is established.
* +0 Strong or weak LPE leverage not awarded: the primitive is a NULL pointer dereference, with no controlled reclaim, arbitrary write, callback control, type confusion, or security-sensitive state modification.
* +0 Confidentiality and integrity not awarded: there is no disclosure path and no unauthorized modification primitive.
* +0 Remote reachability not awarded: the issue is triggered by local driver binding control, not by network traffic.
* +0 Extra availability not awarded: the same NULL dereference crash is already counted once.
* +0 Paranoid escalation not awarded: speculative delegated device-management environments are not enough to override the positively supported host-admin driver-binding requirement.
3. Reachability analysis
The vulnerable path is reached during mlxbf_pmc_probe(). The supplied commit states that any platform driver can be forced to match a non-matching device via device_match_driver_override(), and that this can bind the driver to a device without an ACPI companion. The complete trigger therefore requires control over platform driver binding or driver_override for host platform devices.
This is a host-level device-management operation. No evidence shows that the complete trigger is reachable from an ordinary unprivileged user, a user namespace, a network namespace, or a container-scoped capability. NamespaceScopedPrivilege is therefore NO for the supplied path. No network trigger is established. No race or special timing is required. The driver is hardware/platform-specific, but the decisive reducing factor is host administrative driver-management control, not hardware rarity.
4. Primitive and severity interpretation
The exact primitive is a NULL pointer dereference in mlxbf_pmc_probe(): ACPI_COMPANION() may return NULL, and the old code immediately passed that NULL pointer to acpi_device_hid(). This is a Class C crash/DoS primitive, not a memory-corruption or lifetime primitive.
The issue is not an active structured UAF and not fixed stale storage. There is no cleanup/destructor UAF, no repeated release/refcount mutation, and no post-free state. The demonstrated consequence is kernel oops/crash caused by invalid dereference. The speculative consequence is limited to denial of service because no useful exploitation leverage beyond crash is supported.
ImportantCandidate is NO because there is no Class A primitive and no unresolved Class B lifetime/corruption primitive. AutoDowngradeAllowed is YES because this is a host-admin-triggered NULL dereference with no UAF, no boundary bypass, no confidentiality or integrity impact, and no meaningful unresolved exploitation leverage.
5. One-sentence report phrase
mlxbf_pmc_probe() can dereference a NULL ACPI companion when the driver is force-bound to an incompatible platform device, causing a local host-admin-triggered kernel crash with no evidence of UAF, privilege escalation, or network reachability.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: the patch establishes a straightforward NULL pointer dereference reachable through host-level driver binding control, with DoS-only impact and no unresolved memory-corruption or authorization primitive.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: platform/mellanox: mlxbf-pmc: Check ACPI_COMPANION() against NULL [ Upstream
Commit: 950d8e8375f3ff4787de51b7bdf8dd23a3ad6547
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=950d8e8375f3ff4787de51b7bdf8dd23a3ad6547
Changed files:
drivers/platform/mellanox/mlxbf-pmc.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=950d8e8375f3ff4787de51b7bdf8dd23a3ad6547
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93115 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93115
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:H/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:N/I:N/A:H
The Best / paranoid CVSS score: 5.5
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: 0
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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