[CVE-2026-80918][LOW] HID: core: fix number/pointer type confusion on long items

[CVE-2026-80918][LOW] HID: core: fix number/pointer type confusion on long items

[AL-KERNEL]

CVE: CVE-2026-80918
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: HID: core: fix number/pointer type confusion on long items
Commit: bed7fe3a936b6bdd84671385951397ca673cf6e7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bed7fe3a936b6bdd84671385951397ca673cf6e7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80918
Analysis date: Wed, 09 Sep 2026 13:05:53 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80918 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80918

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-80918	LOW	https://www.kernelcve.org/list/?q=CVE-2026-80918 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:R/S:U/C:L/I:N/A:N';CWE-704;*CWE-200;CWE-843;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '3.5';DESCR 'A crafted HID report descriptor using a long item can make item_udata() or item_sdata() interpret item data.longdata as a numeric short item value. This can print the lower part of a kernel pointer into dmesg as an invalid report_size value, creating a limited information disclosure. For the CVSS the PR:N is used because a malicious HID device does not need an account on the target when it can be connected to the system. The main realistic path is physical USB device attachment, while the paranoid score also considers adjacent wireless HID style exposure with possible user interaction. Impact is limited confidentiality loss only. There is no evidence of memory corruption, kernel crash, or privilege escalation from this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	USB HARDWARE LINUS 	NO	NO	checked

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

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

### 1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2. No floor or cap applied.
* Raw paranoid score: 2
* Paranoid score: 2. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

### 2. Signal breakdown

* +1 Limited confidentiality disclosure. The bug can print the lower part of a kernel pointer into dmesg as an invalid report_size value.
* +1 Broad/default/common subsystem exposure. HID descriptor scanning is a common kernel path exercised when HID devices are attached.

Important non-awarded signals:

* No UAF or lifetime violation is established.
* No arbitrary write, controlled reclaim, OOB write, callback control, or privilege escalation is established.
* Strong semantic reinterpretation is not awarded because the pointer/integer confusion is only consumed as a numeric value for validation/logging, not as active control data.
* Remote network reachability is not established. Physical USB or adjacent wireless HID style exposure is not equivalent to direct network triggering.
* Extra availability is not awarded because no crash or host-wide DoS is demonstrated.
* Integrity impact is not awarded.

### 3. Reachability analysis

The realistic trigger is a malicious or malformed HID device whose report descriptor contains a long item where the pre-scan path expects a short item. A physical USB HID device is the primary path. A paranoid adjacent scenario may exist for wireless HID-like devices, but pairing or user interaction may be required and direct remote reachability is not established.

Host administrator privileges are not required to present a malicious HID device to the system, so HostAdminRequired is NO. Namespace-scoped privilege is not relevant. Reading the leaked value may depend on dmesg or log access policy such as kernel.dmesg_restrict, which limits practical value on hardened systems.

### 4. Primitive and severity interpretation

The primitive is a limited information disclosure caused by number/pointer type confusion in HID item handling. fetch_item() stores a pointer in item->data.longdata for long items, while item_udata() and item_sdata() previously interpreted the same union storage as a short numeric value. The result is a partial kernel pointer value printed to dmesg.

This is not active memory corruption. It is not a UAF, not a repeated release/refcount issue, and not a security-boundary bypass. The demonstrated consequence is limited KASLR-relevant information exposure at most. ImportantCandidate is NO because there is no unresolved strong corruption or privilege-escalation primitive. AutoDowngradeAllowed is YES because the issue is low-impact and suitable for ordinary triage handling.

### 5. One-sentence report phrase

A crafted HID report descriptor using a long item can cause HID pre-scan code to reinterpret a kernel pointer as a numeric field and print partial pointer data to dmesg, resulting in limited information disclosure.

### 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: limited pointer disclosure only, with no UAF, memory corruption, crash, authorization bypass, or privilege-escalation primitive established.

### 7. Call-site confidence

Call-site confidence: high

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

Patch: HID: core: fix number/pointer type confusion on long items
Commit: bed7fe3a936b6bdd84671385951397ca673cf6e7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bed7fe3a936b6bdd84671385951397ca673cf6e7

Commit description:

When fetch_item() is called by hid_scan_report() on an item with
HID_ITEM_TAG_LONG, it stores a pointer to the item data in
item->data.longdata instead of storing a value directly in
item->data.{u8/u16/u32}.

When item_udata() or item_sdata() encounters such an item, it incorrectly
assumes that the item is in short format, and therefore returns the lower
part of a kernel pointer reinterpreted as a number.

When a HID device is connected whose descriptor contains a
HID_GLOBAL_ITEM_TAG_REPORT_SIZE encoded in long format with size=4, this
causes the lower half of a kernel pointer to be printed into dmesg as a
number, like this:

    hid (null): invalid report_size 107953555

To fix it, let item_udata() and item_sdata() verify that the item is in
short format.

Note that this bug only affects hid_scan_report(), while the main parsing
pass hid_parse_collections() will always bail out when encountering a long
item.

Sidenote: There are currently no users of data.longdata; maybe we should
just remove any parsing of long-format descriptors as a follow-up.

Fixes: 3dc8fc0 ("HID: Use hid_parser for pre-scanning the report descriptors")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/hid-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=bed7fe3a936b6bdd84671385951397ca673cf6e7

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

The original Linux kernel CVE announcement for CVE-2026-80918 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80918

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:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS score: 3.5

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: unknown
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).