[CVE-2026-99024][LOW] optee: register TEE devices only once fully initialized [ Upstream

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

CVE: CVE-2026-99024
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: optee: register TEE devices only once fully initialized [ Upstream
Commit: 262062c01f5a817104c88bf6eacb7c6ffdc7018d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=262062c01f5a817104c88bf6eacb7c6ffdc7018d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99024
Analysis date: Tue, 27 Oct 2026 03:10:17 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A permitted local opener can race OP-TEE probe and invoke operations on a prematurely published, partially initialized device, causing a kernel crash or stall.

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

The original Linux kernel CVE announcement for CVE-2026-99024 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99024

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-2026-99024	LOW	https://www.kernelcve.org/list/?q=CVE-2026-99024 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 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:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-362;CWE-665;**CWE-476;BEST CVSS score: '4.7';DESCR 'A race in OP TEE probe made /dev/tee0 and /dev/teepriv0 visible before the associated struct optee was fully initialized. A local process that can open a TEE device during this short window may start a session or invoke operation against a NULL optee ctx or uninitialized mutexes and completions, resulting in a kernel crash or stall. For the CVSS the PR:L value reflects that reliable triggering requires a local process with permission to open the exposed TEE device. AC:H reflects the narrow one time initialization window during driver probe. There is no demonstrated UAF, OOB access, information leak, or controlled write primitive, so the supported impact is availability only. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were 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 KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 4.7 and ActionableScore 1 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.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	INIT HARDWARE LINUS KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

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

1. ActionableScore

* Raw base score: 2.
* Conservative score: 2; no floor or cap applied.
* Raw paranoid score: 2.
* Paranoid score: 2; no separate non-crash primitive supports escalation.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 — Invalid active structured state: published devices permit operations against uninitialized mutexes, completions, caches, and a NULL context.
* +1 — Local below-host-admin trigger: supplied evidence supports a local process with permission to open the TEE device.
* +1 — Plausible kernel crash or stall from NULL dereference or use of uninitialized synchronization objects.
* -1 — Genuinely narrow timing: the device must be opened during the one-time probe interval between registration and initialization.
* No UAF, OOB write, controlled overwrite, reclaim, disclosure, authorization bypass, or integrity effect is shown.
* No additional availability point: crash and stall are the same availability consequence.
* B5-R and B3-PENDING do not apply; there is no retry-accumulated OOB write or shared-backing write.

3. Reachability analysis

The vulnerable nodes become reachable from userspace immediately after `tee_device_register()`. The supplied summary supports a permitted local process rather than host administrator or UID 0 as the trigger. Namespace-scoped access is not established. Triggering requires OP-TEE device presence, driver probe, and winning a short, non-repeatable initialization window; no separate privileged reconfiguration is shown.

4. Primitive and severity reading

The primitive is premature publication of a partially initialized active object. A session or invocation may dereference `optee->ctx == NULL` or operate on uninitialized synchronization state. This is CLASS_C invalid-state/crash behavior, not a lifetime violation or demonstrated memory-corruption primitive. No attacker-shaped state replacement or useful effect past denial of service is shown.

ImportantCandidate is NO because the evidence supports only a narrow crash/stall path. AutoDowngradeAllowed is YES because no unresolved corrupt, ownership, authorization, or trust-boundary primitive remains. B4 is inapplicable: registration timing is an initialization gate, not a mandatory authorization decision changing DENY to ALLOW.

5. One-sentence report phrase

A permitted local opener can race OP-TEE probe and invoke operations on a prematurely published, partially initialized device, causing a kernel crash or stall.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm actual device-node permissions and whether platform-specific reprobe behavior makes the initialization race meaningfully repeatable.

7. Call-site confidence

Call-site confidence: high

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

Patch: optee: register TEE devices only once fully initialized [ Upstream
Commit: 262062c01f5a817104c88bf6eacb7c6ffdc7018d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=262062c01f5a817104c88bf6eacb7c6ffdc7018d

Changed files:
  drivers/tee/optee/ffa_abi.c
  drivers/tee/optee/smc_abi.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=262062c01f5a817104c88bf6eacb7c6ffdc7018d

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

The original Linux kernel CVE announcement for CVE-2026-99024 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99024

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:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: unknown
  Paranoid ActionableScore: 2

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).