[CVE-2026-98247][MODERATE REGULAR] Bluetooth: hci_codec: validate vendor codec count length

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

CVE: CVE-2026-98247
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: hci_codec: validate vendor codec count length
Commit: 9c04b9a4d08b95dee901d24b7607c4cbd65fa0a8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9c04b9a4d08b95dee901d24b7607c4cbd65fa0a8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98247
Analysis date: Sun, 11 Oct 2026 02:37:21 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
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-2026-98247 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98247

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
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CVE-2026-98247	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98247 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:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';CWE-125;*CWE-20;CWE-129;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.6';DESCR 'The Bluetooth HCI supported codec parser can read vnd_codecs num after the skb has ended when a controller reply terminates immediately after the standard codec array. The demonstrated primitive is a one byte out of bounds read whose value is used for a following length check. No direct disclosure channel or write primitive is visible, so the realistic impact is malformed reply rejection or limited availability degradation. A kernel with memory access instrumentation may detect the invalid read and terminate, making a kernel crash possible in the paranoid case. For the CVSS the PR:N is selected because a malicious controller does not need privileges in the host operating system to return the malformed HCI response. AV:P is used because this response normally comes from the local Bluetooth controller and is not directly controlled by a remote Bluetooth peer. Privilege escalation is not supported by the available primitive because there is no UAF, out of bounds write, or arbitrary write. Impact is primarily denial of service and the issue should be reviewed manually because it crosses a hardware trust boundary and performs an out of bounds memory read.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	REMOTE SIMPLEFIX NETWORK SKB LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap changed either score.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Firmware-mediated external influence. A controller controls the HCI command response length, but device or firmware mediation is material and direct radio-triggered reachability is not established.
* +0 Weak corruption concern. The established primitive is a one-byte read beyond the logical end of the skb data.
* +0 Reliable kernel crash. The patch does not establish a production-kernel panic. Reading beyond `skb->len` may remain within allocated skb storage, while diagnostic instrumentation could detect some layouts.
* No negative points were applied. Bluetooth hardware is common enough that a rare-hardware penalty is unsupported.

Important non-awarded signals:

* No heap or slab OOB write is established. B5-R does not apply.
* No retry-accumulated index or offset exists.
* No UAF, controlled reclaim, arbitrary write, disclosure path, or privilege escalation is established.
* Confidentiality was not awarded because the byte is consumed internally and is not returned to userspace, a peer, or the controller.
* Strong availability was not awarded because a host crash is not demonstrated.
* Direct remote reachability was not awarded because the malformed response originates from the local controller rather than a remote Bluetooth peer.
* B3-PENDING does not apply because there is no shared-backing write.
* AuthorizationDecisionBypass and B4-PENDING do not apply because no authorization decision is involved.

3. Reachability analysis

The vulnerable parser processes a malformed Read Local Supported Codecs response supplied by the local Bluetooth controller. An actor controlling a malicious or compromised controller can provide a reply ending immediately after the standard codec array without host UID 0 or host-administrator privileges.

The evidence does not establish that an ordinary remote Bluetooth peer can directly control this controller-generated response. Exploitation therefore remains firmware or peripheral mediated. No user-namespace or network-namespace capability is relevant, no prior host control-plane configuration is required beyond having the controller active, and no race or retry sequence is involved.

4. Primitive and severity interpretation

The exact primitive is a one-byte out-of-bounds read of `vnd_codecs->num` after the skb payload has been fully consumed. The value affects length validation and possibly whether the parser takes the error path, but no subsequent write, externally visible disclosure, or security-sensitive state transition is shown.

This is neither active structured-object corruption nor stale fixed storage. There is no lifetime violation and no repeated release or refcount mutation. The appropriate classification is CLASS_C because the behavior is a constrained invalid read with, at most, diagnostic or availability consequences.

The demonstrated consequence is incorrect parsing of a malformed controller response. A diagnostic-kernel failure is conceivable, but a reliable production-kernel crash is not established. There is no useful exploitation leverage beyond the invalid read, so this is not an Important candidate and automatic downgrade is allowed.

5. One-sentence report phrase

A malformed Bluetooth controller codec response can cause a one-byte read beyond the logical skb payload, but no disclosure, write primitive, reliable host crash, or direct remote trigger is established.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether any affected transport can place the missing count byte at an actual allocation boundary or expose controller-response injection below physical or firmware control. The current evidence does not justify Important preservation.

7. Call-site confidence

Call-site confidence: high

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

Patch: Bluetooth: hci_codec: validate vendor codec count length
Commit: 9c04b9a4d08b95dee901d24b7607c4cbd65fa0a8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9c04b9a4d08b95dee901d24b7607c4cbd65fa0a8

Commit description:

The Read Local Supported Codecs parsers consume the variable-sized
standard codec array before parsing the vendor codec count.  Although the
initial reply-size check includes a vendor count byte in the fixed layout,
it does not guarantee that the byte remains after the standard codec array.

If a controller reply ends immediately after that array, calculating the
vendor codec array size reads vnd_codecs->num beyond the skb data.  Use
skb_pull_data() to validate and consume each codec header before using its
count in both command variants.

Fixes: 8961987 ("Bluetooth: Enumerate local supported codec and cache details")
Fixes: 9ae6640 ("Bluetooth: Add support for Read Local Supported Codecs V2")
Cc: stable@vger.kernel.org
Suggested-by: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Signed-off-by: Laxman Acharya Padhya <acharyalaxman8848@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/bluetooth/hci_codec.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=9c04b9a4d08b95dee901d24b7607c4cbd65fa0a8

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

The original Linux kernel CVE announcement for CVE-2026-98247 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98247

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: unknown
  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).