* [CVE-2026-89729][MODERATE 7.0] HID: sensor-hub: Fix out-of-bounds write in sensor_hub_get_feature
@ 2026-09-12 0:54 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-12 0:54 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-89729
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: HID: sensor-hub: Fix out-of-bounds write in sensor_hub_get_feature
Commit: fa95b14198b6c8ea721b4784f466d3c2c2bac83a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa95b14198b6c8ea721b4784f466d3c2c2bac83a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89729
Analysis date: Fri, 11 Sep 2026 20:54:48 -0400
ActionableScore: 6
ActionableScore lower bound: 5
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-89729 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89729
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: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-89729 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-89729 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-121;*CWE-20;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '6.8';DESCR 'An out of bounds write in the HID sensor hub feature path can occur because sensor_hub_get_feature() clamps the returned size to the caller buffer but the copy loop can still copy bytes based on the HID field report size. A malicious HID descriptor can advertise an oversized feature field while an IIO caller provides a small stack buffer such as one s32, causing kernel memory corruption and likely a crash. For the CVSS the PR:N is used because no privileges are required inside the victim OS once the attacker can present the malicious HID device or descriptor. The issue is not network reachable and is best modeled as a physical or device attached attack surface. Impact is at least denial of service via kernel crash and in the paranoid case may include confidentiality and integrity impact because the primitive is an out of bounds kernel write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 6) YES WRITE OOB USB KPANIC DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=6
ActionableScoreLower=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
1. ActionableScore
* Raw conservative score: 5
* Conservative score: 5. No floor or cap applied.
* Raw paranoid score: 6
* Paranoid score: 6. No floor or cap applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
Positive signals:
* +2 Strong corruption primitive: the patch directly establishes an attacker-influenced out-of-bounds kernel write in `sensor_hub_get_feature()`.
* +1 Firmware/device-mediated external influence: the malformed HID descriptor is supplied by a malicious or compromised HID device rather than by ordinary local kernel-internal state.
* +1 Reliable kernel crash / strong DoS: an OOB write into a small caller buffer, including a possible stack `s32`, realistically supports kernel memory corruption and crash.
* +1 Integrity plausible: the primitive writes beyond a kernel caller-provided buffer, so unauthorized modification of kernel memory is concrete, although target control is constrained.
* Paranoid +1 Weak LPE concern: the overwrite can affect adjacent kernel stack or caller memory, and the attacker can influence descriptor-controlled size and report values. This is enough for unresolved exploitation review, but not enough to claim arbitrary write or proven LPE.
Negative or non-awarded signals:
* RealUAF not awarded: no lifetime or stale-reference primitive is shown.
* Controlled reclaim not demonstrated.
* Arbitrary or directed kernel write not demonstrated.
* Confidentiality not awarded: no read-back or disclosure path is established.
* Remote network reachability not awarded: this is HID/device-attached input, not packet-triggered networking.
* Physical-only rare-hardware penalty not applied: device-attached reachability is already reflected by not awarding remote reachability, and the evidence does not prove an uncommon rare-hardware-only deployment.
* Extra Availability not awarded: the same crash is already counted once.
* Strong LPE +2 not awarded separately: the established primitive is an OOB write, but no callback overwrite, credential overwrite, arbitrary R/W, or demonstrated privilege escalation chain is supplied.
3. Reachability analysis
The likely attacker is someone able to present a malicious HID sensor-hub device or descriptor to the victim system. No host administrator privilege inside the victim OS is required once the malicious device is accepted by the HID stack, so `HostAdminRequired=NO`.
The trigger is not namespace-scoped. User and network namespaces are not relevant to the complete path, so `NamespaceScopedPrivilege=NO`.
The issue is not directly network reachable. It is a physical or device-attached attack surface, possibly relevant to malicious USB/HID-like hardware, compromised embedded sensor hub firmware, or similar device-descriptor trust cases.
No prior host-admin setup is established by the supplied evidence beyond the normal presence of HID sensor-hub support and a caller that requests feature reports. No race is required. The attack is descriptor/state based rather than timing based.
4. Primitive and severity interpretation
The exact primitive is an out-of-bounds kernel write caused by a mismatch between the clamped return size and the per-value copy size. The old loop copied `field->report_size / 8` bytes for each report value even when the caller buffer was smaller. A malicious descriptor could advertise an oversized feature field while an IIO caller supplied a small buffer such as a single `s32`.
This is not a UAF and not a cleanup-only stale pointer. It is an active memory-safety issue with a concrete write beyond the intended buffer. The source bytes come from HID core `__s32` report-value slots, and the destination is caller-provided kernel memory, potentially stack memory.
`PrimitiveClass=CLASS_A` because a concrete attacker-influenced OOB kernel write is directly established. The demonstrated consequence is kernel memory corruption and likely DoS. The speculative consequence is privilege escalation if adjacent kernel memory can be usefully shaped or corrupted, but no complete arbitrary-write or LPE chain is established.
`ImportantCandidate=YES` because kernel OOB write primitives should not be automatically downgraded even when the full exploitation chain is unknown. `AutoDowngradeAllowed=NO` because automatic closure would discard a concrete kernel corruption primitive with unresolved exploitation leverage.
Likely operational severity is Actionable Moderate at minimum, with Strong Important review justified due to the explicit kernel write primitive.
5. One-sentence report phrase
A malicious HID sensor hub descriptor can cause `sensor_hub_get_feature()` to copy beyond a small caller buffer, potentially corrupting kernel stack or caller memory and causing a crash or stronger memory-corruption impact.
6. Manual review recommendation
MANUAL CHECK REQUIRED
Reason: the patch establishes a concrete attacker-influenced kernel out-of-bounds write, and the practical exploitability beyond DoS depends on caller buffer placement, stack layout, descriptor control, and kernel hardening.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: HID: sensor-hub: Fix out-of-bounds write in sensor_hub_get_feature
Commit: fa95b14198b6c8ea721b4784f466d3c2c2bac83a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa95b14198b6c8ea721b4784f466d3c2c2bac83a
Commit description:
sensor_hub_get_feature() clamps its return value to the caller's buffer
size, but the copy loop still copies field->report_size / 8 bytes for
each report value. A malicious HID descriptor can advertise a large
feature field size while an IIO caller supplies a small stack buffer,
such as a single s32, causing an out-of-bounds write.
HID core stores parsed report values in __s32 slots and clamps extracted
values to 32 bits. Reject feature fields that require more than one slot
per value, guard the total byte count calculation, and clamp each
per-value copy to the remaining caller buffer.
Fixes: 5459ada ("HID: sensor-hub: Fix packing of result buffer for feature report")
Cc: [email protected]
Assisted-by: OpenAI:GPT-5.5-Cyber
Signed-off-by: Xingrui Li <[email protected]>
Acked-by: Srinivas Pandruvada <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/hid/hid-sensor-hub.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=fa95b14198b6c8ea721b4784f466d3c2c2bac83a
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-89729 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89729
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:L/A:H
The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The Best / paranoid CVSS score: 6.8
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: 5
Paranoid ActionableScore: 6
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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