* [CVE-2026-98645][IMPORTANT] HID: winwing: fix use-after-free in force feedback teardown [ Upstream
@ 2026-10-24 10:56 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 10:56 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98645
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: HID: winwing: fix use-after-free in force feedback teardown [ Upstream
Commit: 2b25f11ec52ea0a82334d5b83ee321f6b0a35923
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2b25f11ec52ea0a82334d5b83ee321f6b0a35923
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98645
Analysis date: Sat, 24 Oct 2026 06:56:23 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
A force-feedback teardown frees devm-managed Winwing driver state prematurely, leaving active embedded work and causing a later devres double free with slab corruption.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98645 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98645
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98645 IMPORTANT https://www.kernelcve.org/list/?q=CVE-2026-98645 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=5 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_HARD_VETO PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC) 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-415;*CWE-416;CWE-590;*CWE-664;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'The Winwing HID force feedback setup passes devm managed driver data to input_ff_create_memless as an owned context. input_ff_destroy then releases it with kfree, while devres later releases the same allocation again, producing an invalid free and double free. Embedded LED timers and work items can subsequently access freed memory and the repeated release can corrupt the slab allocator during unbind, rmmod, hot unplug, or suspend. For the CVSS the PR:L value is selected because a local user or local policy allowed process may be able to initiate suspend, although direct unbind and rmmod normally require administrative access. The demonstrated impact is a local kernel crash and denial of service. In the paranoid case the confirmed double free, asynchronous UAF exposure, and slab corruption provide a plausible but unproven path to privilege escalation, so CIA:H/H/H is retained with AC:H for heap shaping and timing requirements. The issue is not directly network reachable and requires a supported Winwing device with force feedback initialized. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to IMPORTANT because the CVSS score, vector or bug class threshold rule was applied. final reconciliation stage IMPORTANT to IMPORTANT because a specific evidence based protection or manual review veto was applied and KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were INCREASED_TO_HIGH_BASED_ON_GUESSCVSS and TEMP_KPANIC_MERGE_IMPORTANT_VETO and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 4.1 and ActionableScore 5 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE DANGER USB UAF HARDWARE LINUS INCREASED_TO_HIGH_BASED_ON_GUESSCVSS TEMP_KPANIC_MERGE_IMPORTANT_VETO KPANIC_UNSUPPORTED_REMOVED - - checked
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ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 2.
* Conservative score: 5. REAL UAF FLOOR 5 applied because the first free can end the allocation’s lifetime and devres later frees that exact allocation again; asynchronous timers/work also remain in the freed object.
* Raw paranoid score: 3.
* Paranoid score: 5. The floor subsumes the extra stale-free concern.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
* +2 Real UAF/lifetime violation: `input_ff_destroy()` calls `kfree()` on the devm allocation while embedded LED timers/work can remain active.
* +1 Concrete repeated release: devres retains the same allocation and releases it again during HID teardown.
* +1 Reliable kernel crash/strong DoS: KASAN invalid-free and slab corruption are explicitly reported.
* -2 Specialized physical hardware: the vulnerable path requires a supported Winwing force-feedback HID device.
* Paranoid +1 before flooring: the second free mutates allocator state after the original allocation’s lifetime has ended.
* First release can free the object: yes. Exact allocation survives in devres: yes. Second operation is lifetime-mutating: yes. FLOOR 5 applied.
* No controlled reclaim, attacker-selected payload/target, arbitrary write, disclosure, callback hijack, or LPE is shown. No separate C/I or extra availability point is awarded.
3. Reachability analysis
Trigger paths include unbind, module removal, hot-unplug, and suspend. Unbind and `rmmod` normally require host-administrative authority; the supplied evidence only suggests that local policy may allow a non-admin user to initiate suspend. Therefore complete below-host-admin reachability is unresolved, not proven. No namespace-scoped capability path is involved. The supported physical device and initialized force-feedback path are required; no race is necessary for the initial invalid free/double free.
4. Primitive and severity reading
This is an active structured-object lifetime violation, not merely fixed stale storage. It includes:
A. asynchronous use of freed embedded timer/work state; and
B. a specific second free of the same allocation through devres.
The latter is concrete lifetime corruption rather than an ordinary cleanup dereference. It remains CLASS_B because controlled reclaim, directed corruption, or a useful callback path is not demonstrated. Crash and slab corruption are shown; privilege escalation is speculative. The concrete double free and unresolved post-free allocator effects require Important-vs-Moderate review and prohibit automatic downgrade.
5. One-sentence report phrase
A force-feedback teardown frees devm-managed Winwing driver state prematurely, leaving active embedded work and causing a later devres double free with slab corruption.
6. Manual review advice
MANUAL CHECK REQUIRED
The exact repeated free and asynchronous post-free state leave material exploit leverage unresolved despite the hardware-limited exposure.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: HID: winwing: fix use-after-free in force feedback teardown [ Upstream
Commit: 2b25f11ec52ea0a82334d5b83ee321f6b0a35923
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2b25f11ec52ea0a82334d5b83ee321f6b0a35923
Changed files:
drivers/hid/hid-winwing.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=2b25f11ec52ea0a82334d5b83ee321f6b0a35923
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98645 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98645
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:L/PR:L/UI:N/S:U/C:N/I:N/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: unknown
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: IMPORTANT
KPANIC detected for this report: NO
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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