[CVE-2026-80783][IMPORTANT] HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() [ Upstream

[CVE-2026-80783][IMPORTANT] HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80783
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() [ Upstream
Commit: 26c45abed62536aabf4033fb6d64cf72e93374e9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=26c45abed62536aabf4033fb6d64cf72e93374e9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80783
Analysis date: Fri, 04 Sep 2026 16:38:36 -0400
ActionableScore: 8
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A malicious Magic Mouse compatible HID device can trigger unbounded recursion in magicmouse_raw_event through nested DOUBLE_REPORT_ID reports, causing kernel stack exhaustion and either a panic with CONFIG_VMAP_STACK or possible memory corruption without it.

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

The original Linux kernel CVE announcement for CVE-2026-80783 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80783

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: IMPORTANT
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-2026-80783	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-80783 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H';CWE-674;CWE-121;*CWE-787;Other CVSS 'AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H';BEST CVSS score: '8';DESCR 'A kernel stack overflow in the HID magicmouse driver can occur because magicmouse_raw_event recursively handles DOUBLE_REPORT_ID packets without a recursion depth bound. A malicious HID device matching this driver can send crafted nested double reports up to the HID report buffer limit, causing thousands of nested calls and exhausting the kernel stack. With CONFIG_VMAP_STACK this is expected to cause a kernel panic and denial of service. Without that protection the same bug can become memory corruption with possible confidentiality and integrity impact. For the CVSS the PR:N is used because the attacker does not need privileges on the victim once the malicious HID device is connected or paired. The base vector uses AV:P because a malicious local peripheral is the most typical trigger. The paranoid vector uses AV:A to cover Bluetooth HID proximity scenarios where the attack can be delivered from an adjacent radio range after pairing or device trust is established. Impact should be manually reviewed because the patch context explicitly mentions stack overflow and memory corruption, not only a warning or resource leak.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	OOB DANGER USB HARDWARE LINUS KPANIC PACKET  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=8
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 8
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative score signals:

* Peripheral-mediated external influence: +1. The trigger is a malicious HID device matching the magicmouse driver, not a normal local syscall or network packet.
* Memory corruption, strong corruption primitive: +2. The patch and commit explicitly describe kernel stack overflow and memory corruption when CONFIG_VMAP_STACK is not present.
* Reliable kernel crash / strong DoS: +1. With CONFIG_VMAP_STACK, the expected result is kernel panic.
* Confidentiality impact plausible: +1. Kernel stack overflow without VMAP_STACK can corrupt adjacent kernel memory, so read or disclosure consequences cannot be excluded.
* Integrity impact plausible: +1. The same stack overflow can corrupt kernel memory, making integrity impact plausible.
* Availability impact realistic: +1. The crash is host-wide once the malicious device is accepted and sends crafted reports.
* Physical-only or rare hardware-only condition: -2. The conservative path requires a malicious compatible HID peripheral or equivalent local device presence.

Paranoid additional interpretation:

* Weak LPE concern: +1. Kernel stack overflow is a stronger primitive than a NULL dereference or pure warning, but there is no demonstrated controlled exploit chain.
* Physical-only penalty is not applied in the paranoid score. Bluetooth HID proximity and pairing or trusted-device scenarios can make this closer to adjacent reachability than strictly physical-only USB access.

## 3. Reachability analysis

The bug can be triggered by a malicious HID device that is bound to the magicmouse driver and sends nested DOUBLE_REPORT_ID reports. No privileges are required on the victim after the device is connected or paired, but user interaction or an existing trust relationship is typically needed for Bluetooth HID. This is not network reachable in the IP sense. Containers and namespaces do not materially lower the requirement because the input arrives through the host HID stack, not through a namespaced local API. The path is not broad like TCP or netfilter, but HID drivers are commonly enabled on desktop and workstation kernels, and Bluetooth HID expands practical exposure beyond pure physical USB insertion.

## 4. Severity interpretation

This is not an ordinary Moderate resource bug. The realistic protected-kernel outcome is a reliable local or adjacent-device DoS through kernel panic. The more security-sensitive outcome is kernel stack overflow with memory corruption on configurations without CONFIG_VMAP_STACK or with weaker stack-overflow containment. There is no demonstrated arbitrary write, controlled reclaim, or working privilege-escalation chain, so the conservative interpretation should not assume full LPE. However, explicit stack overflow plus possible memory corruption makes it unsuitable for auto-close and supports Important-candidate manual triage.

## 5. One-sentence report phrase

A malicious Magic Mouse compatible HID device can trigger unbounded recursion in magicmouse_raw_event through nested DOUBLE_REPORT_ID reports, causing kernel stack exhaustion and either a panic with CONFIG_VMAP_STACK or possible memory corruption without it.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.

Reason: the patch explicitly describes kernel stack overflow and memory corruption, not only a warning or DoS-only NULL dereference.

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

Patch: HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() [ Upstream
Commit: 26c45abed62536aabf4033fb6d64cf72e93374e9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=26c45abed62536aabf4033fb6d64cf72e93374e9

Changed files:
  drivers/hid/hid-magicmouse.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=26c45abed62536aabf4033fb6d64cf72e93374e9

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

The original Linux kernel CVE announcement for CVE-2026-80783 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80783

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:P/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 8

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: 5
  Paranoid ActionableScore: 8

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).