[CVE-2026-80723][MODERATE 7.0] of: reserved_mem: prevent OOB when too many dynamic regions are defined [ Upstream

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

CVE: CVE-2026-80723
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: of: reserved_mem: prevent OOB when too many dynamic regions are defined [ Upstream
Commit: 68d27250c9e81ab7764603e346c2b1017cb53adf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=68d27250c9e81ab7764603e346c2b1017cb53adf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80723
Analysis date: Fri, 28 Aug 2026 05:36:32 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
An OOB write in early reserved memory device tree parsing can occur when too many dynamic reserved memory regions are supplied, allowing boot failure or constrained kernel memory corruption if an attacker controls the DTB or equivalent boot input.

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

The original Linux kernel CVE announcement for CVE-2026-80723 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80723

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
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CVE-2026-80723	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.7';DESCR 'An out of bounds write can occur in the reserved memory device tree scan during early boot because dynamically placed reserved memory nodes are stored in a fixed size dynamic_nodes array without a sufficient upper bound check. An attacker would need control over the device tree or boot input provided to the kernel, for example through bootloader firmware or another administrative boot path. For the CVSS the PR:H is used because reliable triggering normally requires high privilege control over boot configuration rather than ordinary local user access. The issue is not network reachable and is not triggered by runtime packet or syscall input. Impact is at least denial of service through boot failure or kernel memory corruption during initialization. Because the primitive is an OOB write in kernel code, the paranoid score keeps C:H I:H A:H for manual review sensitivity.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)  SKIP CVE-2026-80723 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	OOB SIMPLEFIX HARDWARE LINUS  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Triggered signals:

* Firmware-mediated external influence: +1
  The malformed input is the device tree or boot-provided FDT, which is commonly supplied by firmware, bootloader, kexec, or platform provisioning.

* Memory corruption, Strong corruption primitive: +2
  The patch fixes an actual OOB write past the fixed-size `dynamic_nodes[MAX_RESERVED_REGIONS]` array.

* Reliable kernel crash / strong DoS: +1
  The bug occurs during early boot and can plausibly cause boot failure or kernel memory corruption before the system is fully initialized.

* Privileged kernel/device-management memory corruption path: +1
  The corruption occurs in trusted early kernel initialization code while parsing platform memory reservation data.

* Confidentiality impact plausible: +1, paranoid only
  Because this is an OOB write in early kernel memory, broader corruption effects cannot be excluded without manual layout analysis.

* Integrity impact plausible: +1, paranoid only
  Early boot memory corruption could theoretically alter adjacent kernel state, but the patch does not show a controlled overwrite or runtime privilege-escalation primitive.

Subtracted signals:

* Requires admin/root/boot-control privileges in typical deployments: -2
  Reliable triggering normally requires control over the DTB, firmware, bootloader, kexec input, or equivalent administrative boot path.

* Corruption primitive constrained or metadata-only: -1
  The written value is a device-tree node token or offset-like value, not an arbitrary attacker-chosen payload with an attacker-selected target.

* Rare and difficult-to-reach runtime exposure: -1, conservative only
  This is not reachable through normal syscalls, packets, filesystems, or local runtime APIs after boot.

## 3. Reachability analysis

The bug is triggered only when the boot-time device tree defines more than `MAX_RESERVED_REGIONS` dynamically placed `/reserved-memory` nodes. A normal local user cannot usually modify this input. Practical triggering requires control over boot inputs, firmware, bootloader configuration, kexec, or a platform provisioning path that supplies the DTB.

Namespaces and containers do not normally help an attacker reach this path, because the affected code runs during early global kernel initialization before containers exist. The path is common on device-tree based systems, especially ARM and embedded platforms, but the malformed input condition is boot-configuration dependent rather than runtime reachable.

## 4. Severity interpretation

This is not an ordinary low-risk validation bug because the fixed issue is a real OOB write in kernel initialization code. At the same time, it is not a strong Important candidate by default because the trigger requires privileged control over boot-provided platform data and the overwrite primitive appears constrained.

Realistically, this behaves like an actionable Moderate issue for systems where DTB or firmware inputs may be influenced by less trusted provisioning layers. Theoretical impact includes early kernel memory corruption, but practical evidence for local privilege escalation or attacker-controlled code execution is not shown by the patch.

## 5. One-sentence report phrase

An OOB write in early reserved memory device tree parsing can occur when too many dynamic reserved memory regions are supplied, allowing boot failure or constrained kernel memory corruption if an attacker controls the DTB or equivalent boot input.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.

Reason: the issue is a kernel OOB write in early boot code, and although reachability is privileged and constrained, the memory corruption class warrants manual validation of adjacent stack or data layout, DTB control assumptions, and affected platform boot chains.

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

Patch: of: reserved_mem: prevent OOB when too many dynamic regions are defined [ Upstream
Commit: 68d27250c9e81ab7764603e346c2b1017cb53adf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=68d27250c9e81ab7764603e346c2b1017cb53adf

Changed files:
  drivers/of/of_reserved_mem.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=68d27250c9e81ab7764603e346c2b1017cb53adf

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

The original Linux kernel CVE announcement for CVE-2026-80723 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80723

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:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.7

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: 4
  Paranoid ActionableScore: 5

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 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).