* [CVE-2026-98291][MODERATE REGULAR] Bluetooth: btintel_pcie: fix off-by-one bounds check in RX submit [ Upstream
@ 2026-10-10 23:22 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 23:22 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98291
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: btintel_pcie: fix off-by-one bounds check in RX submit [ Upstream
Commit: b5214d72bfdf8ef7744d0c8147e6ebb09b36b259
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b5214d72bfdf8ef7744d0c8147e6ebb09b36b259
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98291
Analysis date: Sat, 10 Oct 2026 19:22:34 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98291 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98291
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 REGULAR
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-2026-98291 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98291 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, 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-193;CWE-129;*CWE-787;*CWE-787;CWE-125;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'An off by one bounds check in btintel_pcie_submit_rx allows frbd_index equal to rxq count to pass validation even though it selects one element beyond the FRBD array. The selected FRBD is updated while preparing a DMA receive submission, so the invalid index creates a plausible out of bounds write into adjacent kernel memory. This may cause corrupted driver state, invalid DMA behavior, or a kernel crash. In a worst case the memory corruption primitive may also affect confidentiality or integrity and could potentially support local privilege escalation if the overwritten data and value are sufficiently controllable. For the CVSS the PR:L reflects a local user or process able to exercise the Bluetooth interface and repeatedly drive RX processing. AC:H reflects the need to reach the exact boundary index and the required device queue state. Direct triggering by a nearby Bluetooth peer is not established because the supplied code does not show reliable remote control over frbd_index.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 2) MAYBE OOB SIMPLEFIX DMAorINTERRUPT IMPROVEONLY LINUS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN5 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=1
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 3
* Paranoid score: 3
* No floor or cap was applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Conservative signals:
* +1 Constrained kernel buffer overwrite. `frbd_index == rxq->count` selects one element beyond the FRBD array, and the surrounding context establishes that the selected FRBD is updated during RX submission.
* +1 Device and DMA descriptor corruption path. The invalid access occurs while preparing a receive buffer descriptor containing DMA-related state.
* -1 No attacker-controlled payload or target is established. The destination is a fixed one-past-end slot, the index comes from device transport state, and the written descriptor values appear kernel or device derived.
Paranoid additions:
* +1 Firmware-mediated external influence. Bluetooth RX activity can plausibly drive RX submission through the controller and firmware, although direct control over `frbd_index` is not established.
* +1 Realistic kernel crash or strong DoS. A one-past-end descriptor write can corrupt adjacent driver state or produce invalid DMA behavior.
* No additional Availability point was awarded because it would duplicate the same possible crash.
* No Strong corruption bonus was awarded because arbitrary target selection, attacker-controlled payload, controlled descriptor replacement, and directed kernel write are not demonstrated.
* No confidentiality, integrity, LPE, or controlled-reclaim points were awarded.
* Direct remote reachability was not awarded because firmware and device state mediate the index.
* B5-R is not established. There is no evidence that the index accumulates across retries because of a missing reset. Attacker control over a retry sequence is also not established, and later consumption of the corrupted adjacent state is not fully visible.
* B4-PENDING does not apply because no authorization decision is involved.
3. Reachability analysis
The complete triggering principal is unresolved. The vulnerable function executes in the Intel PCIe Bluetooth driver and obtains the index from `data->ia.tr_hia[BTINTEL_PCIE_RXQ_NUM]`, which is transport or controller state rather than a direct userspace argument.
A nearby Bluetooth peer can plausibly generate RX activity, but the supplied evidence does not show that it can force the producer index to equal `rxq->count`. This is therefore firmware-mediated influence rather than established direct remote triggering.
It is also not established whether an ordinary local user can drive the complete vulnerable state transition merely by using Bluetooth sockets. No capability, UID 0, namespace, or host-administrator requirement is visible in the supplied context. Accordingly, `HostAdminRequired` and `RequiresHostUID0` remain UNKNOWN rather than being assumed either way.
The path requires compatible Intel PCIe Bluetooth hardware and the `btintel_pcie` driver. This hardware dependency was not scored as rare or physical-only because the supplied evidence does not establish rarity. No race is described. The trigger instead requires the exact boundary index.
4. Primitive and severity interpretation
The exact primitive is a fixed one-past-end FRBD access followed by descriptor preparation. Based on the visible comment that the operation updates the FRBD with a DMA address, this is treated as a constrained kernel OOB write rather than a read-only over-index.
This is not a UAF, repeated release, refcount mutation, authorization bypass, or retry-accumulated B5-R condition. The destination is constrained to the element immediately after the array, and neither the adjacent victim nor meaningful attacker control over the written values is established.
The primitive is CLASS_B because a real kernel descriptor overwrite exists and its adjacent-memory consequences require review. It is not CLASS_A because there is no directed write, arbitrary write, controlled target, controlled payload, reclaim, callback influence, or demonstrated privilege escalation.
The demonstrated technical defect is memory corruption. A kernel crash or invalid DMA operation is a defensible consequence, but stronger non-crash exploitation remains speculative. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` are appropriate because the special B5-R preservation gate is incomplete and no independently useful exploitation leverage is established.
Operationally, this is a borderline Moderate driver corruption issue requiring confirmation of the full write and trigger path, not currently a preserved Important candidate.
5. One-sentence report phrase
An off-by-one check in `btintel_pcie_submit_rx()` permits a one-past-end FRBD update during DMA receive preparation, creating a constrained kernel OOB write whose practical triggerability and adjacent-memory impact remain unresolved.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Review the complete FRBD allocation and update code, the adjacent object layout, the origin and wrap semantics of `tr_hia`, whether Bluetooth traffic can force the boundary value, and whether the malformed descriptor is submitted or consumed before detection.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: Bluetooth: btintel_pcie: fix off-by-one bounds check in RX submit [ Upstream
Commit: b5214d72bfdf8ef7744d0c8147e6ebb09b36b259
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b5214d72bfdf8ef7744d0c8147e6ebb09b36b259
Changed files:
drivers/bluetooth/btintel_pcie.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=b5214d72bfdf8ef7744d0c8147e6ebb09b36b259
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98291 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98291
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:H/PR:L/UI:N/S:U/C:L/I:L/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: 1
Paranoid ActionableScore: 3
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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR
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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