[CVE-2026-99215][MODERATE 7.0] power: supply: core: prevent unregistering a power supply while a callback runs [ Upstream

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

CVE: CVE-2026-99215
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: power: supply: core: prevent unregistering a power supply while a callback runs [ Upstream
Commit: 2ac0256a28e15c4888fa394d1fe66cf7b1d58090
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2ac0256a28e15c4888fa394d1fe66cf7b1d58090
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99215
Analysis date: Thu, 29 Oct 2026 00:26:18 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
A teardown race allows an in-flight power-supply callback to access freed driver data, producing a confirmed UAF and kernel crash without a demonstrated exploitation primitive beyond denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-99215 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99215

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 7.0
Manual review required: YES

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-2026-99215	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-99215 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE_KPANIC RESULT=SAME V39_AEGIS_ONE_STEP_UP=MODERATE->MODERATE_KPANIC (final reconciliation agrees; DECISION: both MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A race allows power_supply_unregister to return while external_power_changed is still using driver data that can then be freed, creating a confirmed use-after-free and observed kernel crash. The trigger requires a narrow timing window and usually depends on privileged device removal or a hardware bus failure shortly after registration. For the CVSS the PR:H base value reflects that ordinary users normally cannot unregister power supply devices. For the CVSS the PR:L paranoid value covers deployments where device management or control of a faulting peripheral is delegated to a less privileged local actor. Availability impact is established. Confidentiality and integrity impact remain hypothetical because no controlled write or reliable reclaim primitive is demonstrated. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 3 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. final reconciliation stage MODERATE to MODERATE_KPANIC because 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 INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V39_AEGIS_ONE_STEP_UP and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 4.1 and ActionableScore 4 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	MAYBE	OOB NULLPTR INIT LEAK UAF KERNEL_PANIC_PLUS_UAF HARDWARE LINUS  INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 KPANIC V39_AEGIS_ONE_STEP_UP MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 2 (+2 confirmed UAF, +1 observed kernel crash, -1 narrow teardown/callback race).
* Conservative score: 2; no UAF floor applies because this is a fixed driver-context teardown race with immediate crash-only behavior.
* Raw paranoid score: 3 (+2 confirmed UAF, +1 observed crash); the timing penalty is withheld because the hardware-failure sequence demonstrably produced callback/removal overlap.
* Paranoid score: 3; no floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +2 — Real UAF: unregister can return and permit devm-managed driver data to be freed while `external_power_changed()` is still executing.
* +1 — Reliable kernel crash: the commit supplies an actual Oops from the callback/workqueue path.
* -1 conservative — Narrow timing: registration must be followed by removal while already queued callback work remains active; the example depends on an immediate bus malfunction.
* No repeated release/refcount signal: unregister and callback race over driver-data lifetime, but no second `put`, `free`, or refcount mutation through the same stale reference is shown.
* No controlled reclaim, attacker-shaped replacement, arbitrary write, disclosure, or authorization bypass is shown.
* No extra availability point: it would duplicate the observed crash.
* No C/I points: the legacy CVSS C:H/I:H possibilities are unsupported by the patch.

3. Reachability analysis

The demonstrated trigger is hardware/driver lifecycle failure: an I2C malfunction causes removal shortly after registration while queued power-supply callbacks run. The evidence does not establish an attacker-invocable userspace interface, ordinary-user trigger, delegated device-management path, or required effective host-admin privilege. Thus `HostAdminRequired` and host UID requirements remain unknown. Power-supply device lifecycle management is not namespace-scoped. No special attacker-controlled retry sequence is shown.

4. Primitive and severity reading

The primitive is a genuine asynchronous use-after-free of fixed driver-owned context during unregister/teardown. The stale callback dereferences driver data after its lifetime can end; the supplied outcome is an immediate invalid dereference and kernel Oops. This is CLASS_B lifetime corruption, but no useful post-free state consumption, replacement control, repeated lifetime mutation, or security-boundary crossing remains demonstrated past the crash. Therefore it is not an Important candidate, and downgrade remains permissible after review.

5. One-sentence report phrase

A teardown race allows an in-flight power-supply callback to access freed driver data, producing a confirmed UAF and kernel crash without a demonstrated exploitation primitive beyond denial of service.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm product-specific device-removal and fault-injection reachability, but the current evidence supports a constrained crash-oriented UAF.

7. Call-site confidence

Call-site confidence: high

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

Patch: power: supply: core: prevent unregistering a power supply while a callback runs [ Upstream
Commit: 2ac0256a28e15c4888fa394d1fe66cf7b1d58090
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2ac0256a28e15c4888fa394d1fe66cf7b1d58090

Changed files:
  drivers/power/supply/power_supply_core.c
  include/linux/power_supply.h

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=2ac0256a28e15c4888fa394d1fe66cf7b1d58090

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

The original Linux kernel CVE announcement for CVE-2026-99215 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99215

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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 2
  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: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).