[CVE-2026-63947][MODERATE 7.0] Bluetooth: HIDP: fix missing length checks in hidp_input_report()

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

CVE: CVE-2026-63947
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: HIDP: fix missing length checks in hidp_input_report()
Commit: 1f08a90013e1e632b34321334e861fcefc056505
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f08a90013e1e632b34321334e861fcefc056505
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63947
Analysis date: Sun, 19 Jul 2026 18:07:18 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-63947 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63947

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: 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
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CVE-2026-63947	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L';CWE-125;CWE-126;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '6.3';DESCR 'Bluetooth HIDP input handling can read beyond the valid skb payload because hidp_input_report() processes keyboard and mouse reports before confirming that enough bytes are present. A paired or compromised Bluetooth HID device can trigger this by sending a truncated input report, which may cause out-of-bounds skb reads and may be interpreted as phantom key presses or spurious mouse movement. For the CVSS the PR:N is used for the paranoid score because the attacker does not need a local user account on the victim once a malicious or compromised HID device is paired. The issue is adjacent network reachable over Bluetooth rather than remotely reachable over IP. Impact is primarily integrity impact through unintended input events, with limited confidentiality and availability impact considered only for the paranoid score due to the out-of-bounds read behavior.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	REMOTE OOB USB SIMPLEFIX NETWORK SKB HARDWARE KPANIC PACKET 	NO	NO	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
* Remote reachable / network-triggerable: +2. The trigger is a malformed Bluetooth HIDP interrupt packet from a paired or compromised HID device. This is adjacent wireless reachability, not Internet remote reachability.
* Weak/limited OOB read primitive: +1 for paranoid scoring. The patch fixes reads past valid skb payload data, but this is read-only OOB and no write, UAF, type confusion, or reclaim primitive is shown.
* Integrity impact plausible: +1. OOB bytes may be interpreted as phantom key presses or spurious mouse movement, which can affect user input integrity.
* Confidentiality impact plausible: +1 only for paranoid scoring. There is an OOB read from skb data, but no clear attacker-visible disclosure channel is demonstrated.
* Availability impact: +0 conservative. No reliable kernel crash is described.
* Broad/default exposure: +0. Bluetooth HIDP is common enough to avoid a rare-subsystem penalty, but triggering requires a paired or compromised HID device.

3. Reachability analysis
A malicious or compromised paired Bluetooth HID device can trigger the bug by sending truncated keyboard or mouse reports. No local user account on the victim is required once the device is paired, so PR:N is reasonable for CVSS-style paranoid analysis. The path is not reachable over ordinary IP networking and requires Bluetooth proximity plus HIDP pairing or compromise of an already trusted device. Namespaces and containers do not materially lower or raise the privilege requirement because the attack source is the external HID device.

4. Severity interpretation
This behaves like an actionable Moderate issue, not a strong Important candidate. The concrete primitive is a limited out-of-bounds read from skb data with possible unintended input events. Theoretical confidentiality impact exists because kernel-adjacent packet memory is read out of bounds, but the patch does not show an attacker-controlled disclosure channel, memory overwrite, UAF, or privilege-escalation primitive. Manual review is still justified because the bug is externally triggerable over Bluetooth and affects the input path.

5. One-sentence report phrase
A paired or compromised Bluetooth HIDP device can send truncated input reports that cause hidp_input_report() to read beyond valid skb payload data, potentially producing phantom keyboard or mouse input and limited OOB-read side effects.

6. Manual review recommendation
MANUAL CHECK RECOMMENDED. The issue is adjacent-network triggerable and includes an OOB read in an input subsystem path, but the demonstrated impact is mainly integrity of input events and no strong memory corruption or LPE primitive is shown.

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

Patch: Bluetooth: HIDP: fix missing length checks in hidp_input_report()
Commit: 1f08a90013e1e632b34321334e861fcefc056505
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1f08a90013e1e632b34321334e861fcefc056505

Commit description:

hidp_input_report() reads keyboard and mouse payload data from an skb
without first verifying that skb->len contains enough data.

hidp_recv_intr_frame() pulls the 1-byte HIDP header before dispatching
to hidp_input_report(). If a paired device sends a truncated packet,
the handler reads beyond the valid skb data, resulting in an
out-of-bounds read of skb data. The OOB bytes may be interpreted as
phantom key presses or spurious mouse movement.

Replace the open-coded length tracking and pointer arithmetic with
skb_pull_data() calls. skb_pull_data() returns NULL if the requested
bytes are not present, eliminating the need for a manual size variable
and the separate skb->len guard.

Fixes: 1da177e ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/bluetooth/hidp/core.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=1f08a90013e1e632b34321334e861fcefc056505

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

The original Linux kernel CVE announcement for CVE-2026-63947 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63947

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:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 6.3

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: YES
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).