[CVE-2026-64276][IMPORTANT] Input: synaptics-rmi4 - bound the F30 keymap to the GPIO/LED count

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

CVE: CVE-2026-64276
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: Input: synaptics-rmi4 - bound the F30 keymap to the GPIO/LED count
Commit: 8c6d18d61bb6fe0e6edf848413391c590552e8a9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c6d18d61bb6fe0e6edf848413391c590552e8a9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64276
Analysis date: Sat, 25 Jul 2026 14:50:48 -0400
ActionableScore: 7
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A Synaptics RMI4 F30 keymap allocation size mismatch can allow a local user with access to the affected input event device to trigger kernel heap out-of-bounds read/write via keycode ioctls, causing DoS and potentially enabling privilege escalation on systems with vulnerable hardware.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64276 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64276

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
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CVE-2026-64276	IMPORTANT	CHECK WITH IMPACT FROM ORIG NN LOW	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-787;CWE-125;CWE-131;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'An out-of-bounds read/write exists in the Synaptics RMI4 F30 input path because gpioled_key_map was allocated for only the capped button range while later code used the full device reported gpioled_count. A device that reports gpioled_count greater than 6 can make rmi_f30_attention read past the allocated keymap, and the EVIOCGKEYCODE or EVIOCSKEYCODE ioctl path can read or write past the same allocation because keycodemax is based on the full count. For the CVSS the PR:L is used because a local user or process with access to the affected input event device can reach the keycode ioctl path, while interrupt based triggering depends on an affected or malicious RMI4 device. The issue is not network reachable. Impact is at least local denial of service via kernel memory corruption, and in the worst case may allow confidentiality or integrity impact including privilege escalation due to kernel heap out-of-bounds read/write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	OOB SIMPLEFIX HARDWARE LINUS KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=6

## 1. ActionableScore

* Conservative score: 6
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  A local process with access to the affected input event device can reach the EVIOCGKEYCODE or EVIOCSKEYCODE ioctl paths.

* Firmware-mediated external influence: +1
  The vulnerable size mismatch depends on the RMI4 device reporting gpioled_count greater than 6.

* Memory corruption, strong corruption primitive: +2
  The patch fixes a real kernel heap out-of-bounds read/write condition. input->keycodemax is based on full gpioled_count while input->keycode pointed to an allocation capped at 6 entries.

* Privilege escalation plausible: +1 conservative, +2 paranoid
  The OOB write is bounded and device-dependent, so conservative scoring treats LPE as plausible but not demonstrated. Paranoid scoring raises this because EVIOCSKEYCODE gives a local user a write path past a kernel heap allocation.

* Reliable kernel crash / strong DoS: +1
  rmi_f30_attention can read beyond the allocation on interrupts, and ioctl based OOB access can realistically crash the kernel.

* Confidentiality impact plausible: +1
  EVIOCGKEYCODE may expose adjacent kernel heap data as keycode values, although the disclosure is likely limited and layout-dependent.

* Integrity impact plausible: +1
  EVIOCSKEYCODE can write beyond the allocated keymap.

Negative / limiting signals:

* Corruption primitive constrained: -1
  The overwrite range is limited by gpioled_count, and exploitation depends on adjacent heap layout and affected hardware.

* Rare or configuration-dependent affected device condition: -1
  Triggerability depends on Synaptics RMI4 F30 with GPIO support and gpioled_count greater than 6 or a malicious/quirky device.

Call-site confidence: high. The commit message explicitly names both rmi_f30_attention and EVIOCGKEYCODE/EVIOCSKEYCODE as affected paths.

## 3. Reachability analysis

The bug is local, not network reachable. A local user or process needs access to the relevant input event device for the ioctl path. On many systems this is not full root, because desktop logind ACLs or input group permissions may grant event device access to an active local session.

The interrupt path depends on the affected RMI4 device reporting gpioled_count greater than 6 with GPIO support enabled. A malicious or abnormal device can influence this state through device query data.

Namespaces do not automatically make this reachable, because input devices are normally host devices and are not broadly exposed into containers unless explicitly passed through. If the device node is delegated into a container, the local trigger may cross a container boundary.

## 4. Severity interpretation

This is not an ordinary Moderate cleanup. It contains a concrete OOB read/write primitive in kernel heap memory, reachable through input subsystem ioctl handling when the affected device state exists.

Realistic exploitation evidence is still limited by hardware dependency, device permissions, and constrained overwrite range. However, the presence of EVIOCSKEYCODE based OOB write makes this clearly actionable and not suitable for auto-close. Conservative handling is Actionable Moderate. Paranoid handling is a Strong Important candidate because local kernel heap OOB write can sometimes be turned into privilege escalation.

## 5. One-sentence report phrase

A Synaptics RMI4 F30 keymap allocation size mismatch can allow a local user with access to the affected input event device to trigger kernel heap out-of-bounds read/write via keycode ioctls, causing DoS and potentially enabling privilege escalation on systems with vulnerable hardware.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch fixes a concrete kernel heap OOB read/write primitive, not just a crash or validation issue, and the local ioctl path gives meaningful attacker interaction with the corrupted object.

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UPSTREAM PATCH SUMMARY
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Patch: Input: synaptics-rmi4 - bound the F30 keymap to the GPIO/LED count
Commit: 8c6d18d61bb6fe0e6edf848413391c590552e8a9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c6d18d61bb6fe0e6edf848413391c590552e8a9

Commit description:

rmi_f30_map_gpios() allocates gpioled_key_map with
min(gpioled_count, TRACKSTICK_RANGE_END) == at most 6 entries, but
rmi_f30_attention() iterates the full f30->gpioled_count (device query
register, range 0..31) and dereferences gpioled_key_map[i], and
input->keycodemax is set to the full gpioled_count while input->keycode
points at the 6-entry allocation.

A device that reports gpioled_count > 6 with GPIO support enabled
therefore causes an out-of-bounds read on the attention interrupt and
out-of-bounds read/write through the EVIOCGKEYCODE/EVIOCSKEYCODE ioctls,
which bound the index only against keycodemax. This is the same defect
as the F3A handler, which was copied from F30.

Size the keymap for the full gpioled_count; the mapping loop still
assigns only the first min(gpioled_count, TRACKSTICK_RANGE_END) entries.

Fixes: 3e64fcb ("Input: synaptics-rmi4 - limit the range of what GPIOs are buttons")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Link: https://patch.msgid.link/20260614-b4-disp-818d6bda-v1-2-cf39a3615085@proton.me
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/input/rmi4/rmi_f30.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=8c6d18d61bb6fe0e6edf848413391c590552e8a9

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

The original Linux kernel CVE announcement for CVE-2026-64276 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64276

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:L/UI:N/S:U/C:L/I:L/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: 6
  Paranoid ActionableScore: 7

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).