[CVE-2026-89627][LOW] HID: roccat: free buffered reports when destroying device

[CVE-2026-89627][LOW] HID: roccat: free buffered reports when destroying device

[AL-KERNEL]

CVE: CVE-2026-89627
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: HID: roccat: free buffered reports when destroying device
Commit: 943b8dc2c6044c01e36395f51bb809a4b6bdfd22
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=943b8dc2c6044c01e36395f51bb809a4b6bdfd22
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89627
Analysis date: Sat, 12 Sep 2026 06:08:53 -0400
ActionableScore: 2
ActionableScore lower bound: 1
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-2026-89627 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89627

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-2026-89627	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89627 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;CWE-404;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.6';DESCR 'A memory leak in the HID roccat driver occurs because buffered report allocations stored in cbuf are not freed when the roccat device is destroyed. roccat_report_event duplicates reports with kmemdup and each slot is only freed when reused, so reports still present at disconnect become unreachable. For the CVSS the PR:N is used for the paranoid score because a malicious or attacker controlled physical HID device can trigger report buffering and device removal without needing a local account on the victim. The issue is not network reachable and normally requires physical device access or an equivalent local hardware emulation setup. Impact is resource exhaustion only and is bounded per device by ROCCAT_CBUF_SIZE report buffers, but repeated device cycles could accumulate leaks and cause denial of service.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	USB INIT SIMPLEFIX LEAK HARDWARE LINUS 	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1. 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

Positive signals:

* +1 Concrete persistent kernel resource/reference leak. `roccat_report_event()` allocates report buffers with `kmemdup()`, and buffered `cbuf[]` entries were not freed when `struct roccat_device` was destroyed.
* Paranoid +1 Possible cumulative resource exhaustion. Repeated device creation, report buffering, and disconnect cycles could accumulate leaked report buffers, but the leak is bounded per device by `ROCCAT_CBUF_SIZE`.

Negative or non-awarded signals:

* RealUAF not awarded. The patch fixes missing frees before device destruction, not stale post-free use.
* CLASS_B not awarded. No UAF, double free, refcount corruption, RCU lifetime mismatch, OOB access, or active stale-object use is established.
* Reliable kernel crash not awarded. The supplied evidence shows kmemdup allocations becoming unreachable, not an immediate panic or fault.
* C/I not awarded. No disclosure, unauthorized modification, memory corruption, or security-boundary bypass is shown.
* Remote reachability not awarded. This is HID device-local behavior, not a network-triggerable path.
* Strong or weak LPE not awarded. No controlled reclaim, arbitrary write, callback control, credential impact, or privilege escalation path is supported.
* Extra availability not awarded beyond the paranoid accumulation point. The same leak is not double-counted as both resource leak and immediate strong DoS.

3. Reachability analysis

The likely attacker model is physical or equivalent local hardware-emulation access to a Roccat-compatible HID device. A malicious or attacker-controlled device can generate buffered reports and then be disconnected or destroyed, causing any still-buffered report allocations to be leaked on vulnerable kernels.

Host-admin-equivalent privilege is not required for the physical-device attacker model, so `HostAdminRequired=NO`. No namespace-scoped privilege is involved, so `NamespaceScopedPrivilege=NO`.

The issue is not network reachable. There is no evidence of a required race. There is a hardware/device prerequisite, but this does not create an Important-grade primitive because the consequence is only a bounded memory leak per device instance.

4. Primitive and severity interpretation

The exact primitive is a missing cleanup of kernel heap allocations stored in `device->cbuf[i].value` before freeing the parent `roccat_device`. This is a persistent resource leak, not a UAF.

The affected storage is fixed buffered report storage associated with a HID device. The demonstrated consequence is unreachable allocations after device destruction. There is no active structured stale object, no cleanup stale dereference, and no concrete repeated release/refcount mutation.

PrimitiveClass is `NONE` because no meaningful corruption, lifetime-after-free use, authorization bypass, or ownership violation is established. The likely operational severity is Low to ordinary Moderate. Paranoid scoring can account for repeated leak accumulation, but it remains a resource-exhaustion-only issue.

ImportantCandidate is `NO` because the bug does not establish a kernel corruption or security-boundary primitive. AutoDowngradeAllowed is `YES` because the issue is a bounded device-local resource leak without unresolved exploitation leverage.

5. One-sentence report phrase

A bounded memory leak in the HID roccat driver can leave buffered report allocations unreachable when a device is destroyed, allowing possible resource exhaustion only after repeated physical or equivalent HID device cycles.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a concrete but bounded memory leak with no UAF, no memory corruption, no network reachability, no authorization bypass, and no plausible privilege-escalation primitive shown by the patch.

7. Call-site confidence

Call-site confidence: high

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

Patch: HID: roccat: free buffered reports when destroying device
Commit: 943b8dc2c6044c01e36395f51bb809a4b6bdfd22
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=943b8dc2c6044c01e36395f51bb809a4b6bdfd22

Commit description:

roccat_report_event() duplicates each report with kmemdup() and stores
the allocation in a circular-buffer slot. The allocation is released only
when that slot is reused.

The device destruction paths free struct roccat_device without releasing
reports still stored in cbuf[]. This makes those allocations unreachable
and leaks up to ROCCAT_CBUF_SIZE report buffers per device.

Add a small destructor that frees every buffered report before freeing the
device, and use it in both paths that can destroy a registered device.

Fixes: 206f5f2 ("HID: roccat: propagate special events of roccat hardware to userspace")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/hid/hid-roccat.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=943b8dc2c6044c01e36395f51bb809a4b6bdfd22

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

The original Linux kernel CVE announcement for CVE-2026-89627 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89627

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:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.6

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: 1
  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).