* [CVE-2026-97515][LOW] i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845 [ Upstream
@ 2026-09-24 18:22 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-24 18:22 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-97515
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845 [ Upstream
Commit: e9b139c4684ed8593a0b779ca02ea05f460b2eec
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9b139c4684ed8593a0b779ca02ea05f460b2eec
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97515
Analysis date: Thu, 24 Sep 2026 14:22:42 -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-2026-97515 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97515
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-2026-97515 LOW https://www.kernelcve.org/list/?q=CVE-2026-97515 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-835;**CWE-400;CWE-754;BEST CVSS score: '4.6';DESCR 'An I3C target holding SDA low can cause a false Master Request event on NPCM845. The driver emits STOP to recover the bus, but STOP can spuriously raise SLVSTART and repeatedly re enter Master Request handling. This creates an IRQ storm that can lock up a CPU and cause denial of service. For the CVSS the PR:N because an attacker controlling a physically connected I3C target does not require a local account or operating system privileges. The attack requires physical access to the I3C bus or control of a connected target device. It is not network reachable. No confidentiality or integrity impact is supported because the issue is an interrupt feedback loop and does not provide a memory corruption primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES DMAorINTERRUPT HARDWARE LINUS NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
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 score floor: -1 -> 0 because ActionableScore cannot be negative.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash / strong DoS. The documented IRQ feedback loop can indefinitely retrigger the interrupt handler and lock up a CPU.
* -2 Physical-only or rare hardware-only requirement. The issue requires an NPCM845 controller and an I3C target that can hold SDA low or otherwise induce the relevant bus condition.
* No remote reachability bonus. Network traffic does not reach the affected I3C interrupt path.
* No firmware-mediated external influence bonus. The supplied evidence establishes a stuck physical I3C target condition, not a remotely controllable firmware interface.
* No corruption signal. The patch establishes an interrupt status feedback loop, not UAF, OOB access, invalid lifetime handling, or a write primitive.
* No confidentiality or integrity signal. There is no demonstrated data disclosure, unauthorized modification, or security-boundary bypass.
* No additional Availability point. The CPU lockup is already counted as the strong DoS consequence.
3. Reachability analysis
The triggering condition is a physical I3C bus condition on NPCM845. A malicious or malfunctioning I3C target that holds SDA low can induce a false Master Request event, after which the controller and driver can loop on STOP and false SLVSTART handling.
Host administrator privileges are not required for the physical-attacker model, because controlling a connected I3C target does not require a local operating system account or kernel capability. However, the attack requires access to the relevant hardware bus or control over a physically attached target device.
No network namespace, user namespace, delegated capability, sysctl, or host control-plane operation is involved. The complete trigger is not namespace-scoped. The issue is limited to systems using the affected SVC I3C controller driver with the NPCM845 false SLVSTART hardware quirk.
4. Primitive and severity interpretation
The exact primitive is an interrupt feedback loop:
false Master Request event -> driver emits STOP -> false SLVSTART status -> IRQ retrigger -> another STOP.
This is not a stale-object, lifetime, ownership, refcount, DMA corruption, or memory corruption issue. There is no active structured object reuse, no cleanup/destructor UAF, and no repeated lifetime mutation.
The demonstrated consequence is CPU lockup and denial of service. A broader host failure may occur if the affected CPU services critical work, but the patch does not establish privilege escalation, arbitrary kernel access, data disclosure, integrity impact, or cross-boundary compromise.
PrimitiveClass is NONE because the defect is a hardware-specific interrupt-state handling error without an independently useful corruption or authorization primitive. ImportantCandidate is NO and AutoDowngradeAllowed is YES because the established effect is hardware-local DoS with a physical prerequisite and no unresolved memory-corruption leverage.
5. One-sentence report phrase
A false SLVSTART interrupt condition on NPCM845 can create an I3C interrupt feedback loop after a target holds SDA low, causing an IRQ storm and CPU denial of service through physical bus access.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The patch establishes a hardware-specific IRQ storm and CPU DoS only. No memory corruption, authorization bypass, remote path, or privilege-escalation primitive is shown.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845 [ Upstream
Commit: e9b139c4684ed8593a0b779ca02ea05f460b2eec
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9b139c4684ed8593a0b779ca02ea05f460b2eec
Changed files:
drivers/i3c/master/svc-i3c-master.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=e9b139c4684ed8593a0b779ca02ea05f460b2eec
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-97515 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97515
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:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.6
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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