[CVE-2026-97976][MODERATE REGULAR] Bluetooth: btintel_pcie: validate packet_len before skb_put_data [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-97976
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: btintel_pcie: validate packet_len before skb_put_data [ Upstream
Commit: ab0159b1f7214ce9bad9862751e4553e635a21b1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ab0159b1f7214ce9bad9862751e4553e635a21b1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97976
Analysis date: Fri, 25 Sep 2026 15:42:01 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97976 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97976

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: NO

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

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

CVE-2026-97976	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97976 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;CWE-1284;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'An out-of-bounds read in the Intel Bluetooth PCIe transport occurs because btintel_pcie_submit_rx_work trusts packet_len from an RFH header before copying data with skb_put_data. A packet_len larger than the RX buffer can make the kernel read past the transport buffer, which may cause a kernel fault or copy adjacent memory into an SKB. An ordinary remote Bluetooth peer is not expected to control this PCIe transport header. Triggering normally requires a malicious or compromised Bluetooth controller firmware, or local control over the affected device or firmware. For the CVSS the PR:L value is used for the paranoid score because a local service account or reduced capability administrator with delegated Bluetooth device or firmware control may be sufficient in some deployments. Impact is at least local denial of service. Limited confidentiality impact is plausible if copied out-of-bounds data becomes observable through subsequent HCI processing, but this requires manual verification. No integrity impact or privilege escalation primitive is demonstrated by the patch.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	OOB SIMPLEFIX ERRORPATH PACKET  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	YES	NO	guess

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap was applied.

2. Signal breakdown

Conservative score:

* +0 Limited out of bounds read. The patch establishes an unchecked length used by skb_put_data, but does not establish a user visible disclosure, a write primitive, controlled target selection, or a reliable crash.
* +0 No direct remote reachability. The attacker controlled value originates in the PCIe Bluetooth controller firmware header, not in an ordinary remote Bluetooth packet.
* +0 No reliable kernel crash awarded. An out of bounds source read may fault depending on allocation layout, but the supplied patch does not demonstrate an Oops, panic, or repeatable host wide denial of service.
* +0 No confidentiality point. Bytes read past the RX buffer are copied into an SKB, but the supplied evidence does not show that those bytes become observable to userspace, a remote peer, or another disclosure sink.
* +0 No integrity point. No out of bounds write, object overwrite, refcount mutation, callback control, or ownership violation is established.
* +0 No Local unprivileged trigger point. The supplied evidence demonstrates reproduction with customized controller firmware or by modifying the kernel driver, but does not establish that an ordinary local user can perform the complete trigger sequence.
* +0 No host administrator penalty. Host administrator privilege may be necessary to install or replace controller firmware, but this is not positively established for every possible affected deployment.

Paranoid score:

* +1 Firmware mediated external influence. The patch explicitly confirms that customized controller firmware can generate the invalid packet_len value. This is a technically supported malicious device or compromised firmware attacker model, but it is not direct network reachability.

Important non awarded signals:

* Controlled reclaim is not demonstrated.
* Arbitrary or directed kernel write is not demonstrated.
* Real UAF, stale object use, double free, or repeated refcount mutation is not demonstrated.
* Remote Bluetooth reachability is not established because an ordinary Bluetooth peer does not normally control the PCIe RFH packet_len field.
* Reliable host crash is not established.
* Information disclosure is not established because the later HCI and SKB consumption path is not supplied.
* Privilege escalation is not established.
* No concrete security boundary bypass exists.

3. Reachability analysis

The vulnerable value is packet_len in an RFH header received from the Intel Bluetooth PCIe controller. The supplied commit states that the issue can be simulated with customized firmware that returns an oversized packet_len, or by directly modifying rfh_hdr packet_len in the driver before calling btintel_pcie_submit_rx_work.

The evaluated attacker model is therefore a malicious or compromised Bluetooth controller firmware, or an actor with local control over the affected Bluetooth device or its firmware. This is not equivalent to a remote Bluetooth peer controlling a normal HCI packet. A remote adjacent Bluetooth attacker is not shown to be able to modify the PCIe transport header generated by the controller firmware.

The complete privilege boundary is unresolved. Firmware installation or controller replacement may require host administration in common deployments, but the patch does not establish that this is always required. Conversely, it also does not establish that an ordinary local user, a namespace user, or a delegated Bluetooth service can perform the complete trigger sequence. Therefore HostAdminRequired and NamespaceScopedPrivilege are UNKNOWN.

No namespace scoped capability path, user namespace path, network namespace path, or ordinary unprivileged local trigger is established. No race is involved.

4. Primitive and severity interpretation

The exact primitive is an out of bounds read from the fixed Bluetooth PCIe RX buffer. btintel_pcie_submit_rx_work reads packet_len from the RFH header and previously accepted any positive value. skb_put_data can then copy more bytes than remain in the BTINTEL_PCIE_BUFFER_SIZE transport buffer.

This is not a UAF, lifetime violation, double release, refcount corruption, active structured object reuse, or attacker controlled out of bounds write. The available evidence establishes an invalid source read only. The immediate practical consequence may be malformed HCI processing or a kernel fault if the out of bounds source access crosses into an invalid mapping, but a reliable crash is not demonstrated.

A limited confidentiality concern is possible only if bytes copied beyond the RX buffer later become externally observable through HCI processing or another output path. That path is not visible in the supplied code. No integrity effect, controlled kernel corruption, arbitrary read, arbitrary write, callback influence, or privilege escalation mechanism is established.

PrimitiveClass is CLASS_C because the demonstrated issue is an invalid bounds state with potential crash behavior, without an independently useful corruption primitive. ImportantCandidate is NO because there is no established exploitation leverage beyond the limited out of bounds read. AutoDowngradeAllowed is YES because no unresolved Class A or meaningful Class B lifetime or corruption primitive is present.

The likely operational severity is Low or ordinary Moderate. The issue should still receive targeted review because it is a kernel memory safety defect involving firmware supplied length data.

5. One-sentence report phrase

An Intel Bluetooth PCIe controller firmware supplied packet_len value can cause btintel_pcie_submit_rx_work to read beyond its RX buffer during skb_put_data, but the supplied evidence establishes neither direct remote Bluetooth reachability nor a write or privilege escalation primitive.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Verify the complete skb and HCI receive path to determine whether copied out of bounds bytes can reach a userspace visible interface or whether oversized reads can reliably fault the kernel. Also verify whether affected controller firmware can be updated or influenced by a below host administrator attacker in the evaluated product.

7. Call-site confidence

Call-site confidence: medium

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

Patch: Bluetooth: btintel_pcie: validate packet_len before skb_put_data [ Upstream
Commit: ab0159b1f7214ce9bad9862751e4553e635a21b1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ab0159b1f7214ce9bad9862751e4553e635a21b1

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=ab0159b1f7214ce9bad9862751e4553e635a21b1

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

The original Linux kernel CVE announcement for CVE-2026-97976 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97976

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:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.3

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: 0
  Paranoid ActionableScore: 1

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).