[CVE-2026-64081][MODERATE REGULAR] firmware: arm_ffa: Validate framework notification message layout [ Upstream

[CVE-2026-64081][MODERATE REGULAR] firmware: arm_ffa: Validate framework notification message layout [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64081
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: firmware: arm_ffa: Validate framework notification message layout [ Upstream
Commit: 3c51d99449dc5a01c08a7fce6071d6721f5aac83
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c51d99449dc5a01c08a7fce6071d6721f5aac83
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64081
Analysis date: Sun, 19 Jul 2026 21:28:39 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
Malformed ARM FF-A framework notification metadata can cause the kernel to use unvalidated offset and size fields from the shared RX buffer, leading to an OOB read or oversized allocation risk with firmware-mediated DoS and limited confidentiality impact.

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

The original Linux kernel CVE announcement for CVE-2026-64081 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64081

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 REGULAR
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
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CVE-2026-64081	MODERATE	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H';*CWE-20;CWE-125;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.1';DESCR 'The ARM FF-A framework notification handler used firmware supplied offset and size fields from the shared RX buffer before validating the message layout. Malformed firmware data could make kmemdup() copy from outside the valid notification payload or request an oversized allocation, which creates an OOB read and denial of service risk. For the CVSS the PR:H is used because reliable triggering normally requires control over firmware or an FF-A component that can generate framework notifications, not only ordinary local user access. The issue is not network reachable and is specific to affected ARM FF-A platforms. Impact is mainly denial of service with limited confidentiality risk from OOB read. Integrity impact is not supported because the primitive is read and allocation abuse, not an OOB write or arbitrary write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4)  SKIP CVE-2026-64081 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	OOB SIMPLEFIX LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1
  The malformed values come from the FF-A framework notification message in the shared RX buffer, not from an ordinary local syscall path.

* Reliable kernel crash / strong DoS: +1
  Unvalidated offset and size can make `kmemdup()` read outside the valid RX buffer or request an oversized allocation. This can plausibly cause kernel fault or memory pressure.

* Confidentiality impact plausible: +1
  The primitive is an OOB read into a kernel allocation. There is no clear user-visible disclosure path in the provided patch, so this is limited and not treated as high confidence.

Paranoid additional signal:

* Privileged firmware/device-management path: +1
  The bug is in a trusted firmware communication path where malformed firmware-controlled metadata drives kernel memory access. This deserves manual review even though attacker control is indirect.

Negative signal:

* Rare / platform-specific exposure: -1
  The issue is specific to ARM FF-A systems with framework notifications and requires a malformed firmware or FF-A component message.

Not awarded:

* No remote/network-triggerable bonus.
* No local unprivileged trigger bonus.
* No generic strong memory corruption bonus because the patch shows OOB read and allocation abuse, not OOB write, UAF, double free, or arbitrary write.
* No privilege escalation bonus because no reclaim, overwrite, callback control, refcount abuse, or type confusion primitive is shown.

## 3. Reachability analysis

Triggering requires a malformed FF-A framework notification delivered through the shared RX buffer. In typical deployments this means influence over firmware, a secure-world component, or another FF-A endpoint capable of generating framework notifications. An ordinary local unprivileged user is not expected to directly reach this path.

Namespaces and containers do not meaningfully lower the privilege requirement because the input source is firmware-mediated rather than a namespaced Linux userspace API. The path is not network reachable. Exposure depends on ARM platforms using FF-A framework notification support, so it is not a broad default Linux attack surface.

Call-site confidence: high for the immediate `kmemdup()` and UUID parsing path because the relevant function context is present. Medium for downstream disclosure impact because the provided patch does not show how `buf` is later consumed by callbacks.

## 4. Severity interpretation

This behaves more like a borderline actionable Moderate than an Important-class vulnerability. The realistic impact is firmware-mediated DoS with limited OOB-read concern. Theoretical confidentiality impact exists because kernel memory adjacent to the RX buffer may be copied, but the patch does not show a direct disclosure channel to an unprivileged attacker.

The issue should not be escalated to strong memory corruption or LPE. The primitive is not an OOB write, UAF, type confusion, double free, or arbitrary write. The main reason for manual review is that trusted firmware-controlled layout fields directly drive kernel memory reads and allocation size.

## 5. One-sentence report phrase

Malformed ARM FF-A framework notification metadata can cause the kernel to use unvalidated offset and size fields from the shared RX buffer, leading to an OOB read or oversized allocation risk with firmware-mediated DoS and limited confidentiality impact.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because the bug includes a firmware-controlled OOB read primitive in a trusted kernel firmware interface, but it is not directly reachable by local unprivileged users or the network and does not show a concrete write or privilege-escalation primitive.

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

Patch: firmware: arm_ffa: Validate framework notification message layout [ Upstream
Commit: 3c51d99449dc5a01c08a7fce6071d6721f5aac83
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c51d99449dc5a01c08a7fce6071d6721f5aac83

Changed files:
  drivers/firmware/arm_ffa/driver.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=3c51d99449dc5a01c08a7fce6071d6721f5aac83

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

The original Linux kernel CVE announcement for CVE-2026-64081 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64081

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:L/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.1

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: 3
  Paranoid ActionableScore: 4

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).