[CVE-2026-98565][LOW] net: dsa: mt7530: fix NULL dereference on unbind of MT7531 and MT7621 [ Upstream

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

CVE: CVE-2026-98565
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: dsa: mt7530: fix NULL dereference on unbind of MT7531 and MT7621 [ Upstream
Commit: bd172580e624bac00d83abd5c4320d2e14d853bc
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd172580e624bac00d83abd5c4320d2e14d853bc
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98565
Analysis date: Sat, 24 Oct 2026 05:37:12 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
Privileged removal of an affected MediaTek switch can dereference NULL regulator pointers and crash the kernel.

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

The original Linux kernel CVE announcement for CVE-2026-98565 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98565

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.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98565	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98565 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC)	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-670;CWE-754;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'The MT7530 DSA driver can call regulator_disable with NULL core_pwr and io_pwr pointers while removing an MT7531 or MT7621 device because those regulators are initialized only for ID_MT7530. The demonstrated primitive is a NULL pointer dereference during rmmod or sysfs unbind, which can cause a kernel oops or panic and affect availability. For the CVSS the PR:H value reflects that module removal or host device unbind normally requires administrative capabilities. For the CVSS the PR:L value in the paranoid vector covers deployments that delegate device lifecycle control to a restricted service or container. There is no supported UAF, OOB access, information leak, controlled write, or privilege escalation primitive, and the issue is not remotely reachable. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.3 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	NULLPTR SIMPLEFIX ERRORPATH NETWORK LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: -1.
* Conservative score: 0 after clamping the negative result to the score minimum.
* Raw paranoid score: -1.
* Paranoid score: 0.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash/strong DoS: MT7531 and MT7621 removal passes NULL `core_pwr` and `io_pwr` pointers to `regulator_disable()`, plausibly causing an oops or panic.
* -2 Host-administrator-equivalent trigger: the evidenced paths are module removal and sysfs device unbind, which require host device/module lifecycle authority.
* No UAF, OOB access, write primitive, refcount mutation, disclosure, authorization bypass, or attacker-controlled structured-state corruption is shown.
* No additional availability point: it would duplicate the same NULL-dereference crash.
* No hardware-rarity penalty: affected hardware is required, but the evidence does not establish that it is sufficiently rare for an additional reduction.
* NEW52/B5-R and NEW53/B3-PENDING do not apply: there is neither an OOB write nor a shared-backing write.

3. Reachability analysis

A host administrator can trigger removal through `rmmod` or sysfs unbind on an affected MT7531/MT7621 device. Numeric host UID 0 is not inherently required because the relevant effective capabilities may be held by another principal, but no below-host-admin complete trigger is evidenced. Namespace-scoped capability sufficiency, delegated unbind access, and remote reachability are not shown. No race is required.

4. Primitive and severity reading

The exact primitive is a deterministic NULL-pointer dereference during privileged device teardown. It is Class C crash/DoS behavior, not a lifetime violation or useful corruption primitive. The fix confines regulator shutdown to the only device ID for which the regulator pointers are initialized. ImportantCandidate is NO and auto-downgrade is allowed because no unresolved non-crash exploit or trust-boundary mechanism remains.

5. One-sentence report phrase

Privileged removal of an affected MediaTek switch can dereference NULL regulator pointers and crash the kernel.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch supports only a host-admin-triggered NULL dereference with availability impact.

7. Call-site confidence

Call-site confidence: high

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

Patch: net: dsa: mt7530: fix NULL dereference on unbind of MT7531 and MT7621 [ Upstream
Commit: bd172580e624bac00d83abd5c4320d2e14d853bc
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd172580e624bac00d83abd5c4320d2e14d853bc

Changed files:
  drivers/net/dsa/mt7530-mdio.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=bd172580e624bac00d83abd5c4320d2e14d853bc

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

The original Linux kernel CVE announcement for CVE-2026-98565 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98565

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).