[CVE-2023-7356][IMPORTANT] Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID [ Upstream

[CVE-2023-7356][IMPORTANT] Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID [ Upstream

[AL-KERNEL]

CVE: CVE-2023-7356
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID [ Upstream
Commit: ba25efe15e8fd909884e113a86c6ccd07d88256e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ba25efe15e8fd909884e113a86c6ccd07d88256e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2023-7356
Analysis date: Wed, 21 Oct 2026 22:08:18 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A nearby Bluetooth transmitter can supply an oversized Periodic Advertisement Report that is copied into a smaller BASE buffer, causing a limited kernel OOB write and potentially allowing adjacent bytes to be returned through the ISO_BASE getsockopt path.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2023-7356 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2023-7356

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2023-7356	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2023-7356 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT 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:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-787;*CWE-20;CWE-120;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.5';DESCR 'A memory corruption issue exists in the Bluetooth ISO path because iso_connect_ind copied the complete Periodic Advertisement Report into the fixed size BASE buffer without validating the destination size or confirming that the data belonged to the Basic Audio Announcement Service. A nearby Bluetooth transmitter may provide a crafted report whose length exceeds the BASE capacity, causing an out of bounds write into adjacent kernel object data. For the CVSS the PR:N value is selected because the transmitting attacker does not need an account or privileges on the target and only needs Bluetooth radio reachability. AV:A and AC:H reflect that exploitation requires proximity and a suitable Bluetooth ISO listener and periodic advertising synchronization state. Impact is at least denial of service through kernel state corruption or a crash. In the worst case the concrete kernel out of bounds write may affect confidentiality and integrity or support privilege escalation, but reliable code execution is not established and requires manual validation of the overwritten fields and object layout. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 7.5 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 KP and FD specialist checks stage IMPORTANT to IMPORTANT because a specific evidence based protection or manual review veto was applied. final reconciliation stage IMPORTANT to IMPORTANT because 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 V33_ACTIVE_STATE_BOUNDARY_CANDIDATE and IMPORTANT_CANDIDATE_MANUAL_REVIEW and KP_ONLY_DOWNGRADE_VETO and V42_LEGACY_CLASSA_FD_VETO and MANUAL_REVIEW_REQUIRED and TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 3.1 and ActionableScore 1 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	REMOTE NETWORK LINUS CVEOUTDATED V33_ACTIVE_STATE_BOUNDARY_CANDIDATE IMPORTANT_CANDIDATE_MANUAL_REVIEW KP_ONLY_DOWNGRADE_VETO V42_LEGACY_CLASSA_FD_VETO MANUAL_REVIEW_REQUIRED TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	guess

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 5
* Raw paranoid score: 5
* Paranoid score: 5
* Applied conservative floor: 3 -> 5 because an attacker-influenced kernel OOB write is established and must not be automatically downgraded.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 Strong corruption primitive. `ev3->length` controls the size of a `memcpy()` from a Periodic Advertisement Report into the smaller fixed-size `iso_pi(sk)->base` buffer.
* +1 Firmware-mediated external influence in the conservative score. Bluetooth radio input is delivered through the controller as `HCI_EV_LE_PER_ADV_REPORT`.
* +2 Direct adjacent-network trigger in the paranoid score, replacing the firmware-mediated +1. A nearby transmitter can influence the Periodic Advertisement Report consumed by the vulnerable path when the victim has a matching ISO listener and synchronization state.
* +1 Plausible confidentiality impact. The visible `ISO_BASE` getsockopt path uses `base_len` to copy `base` to userspace. The vulnerable code records the untrimmed report length, so a length larger than the BASE array can potentially cause a limited read beyond `base`.
* +1 Strong DoS in the paranoid score. Overwriting fields adjacent to an active kernel socket object can plausibly cause an invalid state or kernel fault, although no deterministic panic is demonstrated.
* -1 Constrained overwrite. The apparent maximum overflow is small because `BASE_MAX_LENGTH` differs from `HCI_MAX_PER_AD_LENGTH` by `EIR_SERVICE_DATA_LENGTH`, and no arbitrary target selection is established.

Not awarded:

* No UAF, controlled reclaim, arbitrary write, callback overwrite, or privilege escalation is demonstrated.
* No additional integrity point is awarded because the exact adjacent field and a security-sensitive downstream effect are not established.
* V33 is not independently established because no specific privileged downstream consumer of the overwritten adjacent field is shown.
* B5-R does not apply because there is no retry-accumulated index or offset.
* B3-PENDING does not apply because no shared or file-backed storage is involved.
* B4-PENDING does not apply because this is not an authorization decision bypass.

3. Reachability analysis

The external input originates from a nearby Bluetooth transmitter and reaches the kernel through a controller-generated Periodic Advertisement Report. The attacker does not need a host account, host UID 0, or a host capability. A suitable Bluetooth ISO listener and periodic-advertising synchronization state must already exist on the victim, so arbitrary unsolicited Bluetooth traffic is not sufficient.

The complete radio-side trigger is adjacent-network rather than Internet-reachable. No user-namespace or network-namespace capability is part of that external attacker model. Bluetooth hardware and ISO support are required, but the supplied evidence does not justify treating them as rare physical-only prerequisites or applying an additional hardware penalty.

There is no race or retry sequence. Trigger reliability depends on producing an accepted Periodic Advertisement Report with a length exceeding the BASE capacity.

4. Primitive and severity interpretation

The exact primary primitive is an attacker-influenced heap or slab OOB write into memory following `iso_pi(sk)->base`. The destination belongs to an active structured socket object rather than fixed disposable transfer storage. The source bytes and copy length originate from externally influenced advertisement data, but the overwrite width is limited and the exact adjacent victim field is not supplied.

A secondary potential primitive is a limited kernel OOB read through `iso_sock_getsockopt()`. The vulnerable producer stores the full report length in `base_len`, while the consumer can copy that length from the smaller BASE array to userspace. Exploitability of this disclosure depends on who can own and query the affected ISO socket, so a complete low-privilege disclosure chain remains unresolved.

This is CLASS_A because a concrete attacker-influenced kernel OOB write is established. Demonstrated or directly supported consequences are corruption of an active socket object and a possible limited disclosure. Kernel crash is plausible but not guaranteed. Arbitrary kernel read or write, LPE, and reliable code execution are not established.

ImportantCandidate is YES because the exact overwritten fields, object layout, and later consumers require manual review. AutoDowngradeAllowed is NO because automatically treating the issue as crash-only would discard a concrete externally influenced write and the visible potential copy-to-userspace consequence.

5. One-sentence report phrase

A nearby Bluetooth transmitter can supply an oversized Periodic Advertisement Report that is copied into a smaller BASE buffer, causing a limited kernel OOB write and potentially allowing adjacent bytes to be returned through the ISO_BASE getsockopt path.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Confirm the full `struct iso_pinfo` layout, maximum accepted report length, overwritten adjacent fields, ISO socket privilege requirements, and whether `base_len` can expose bytes beyond `base` to an attacker-controlled userspace process.

7. Call-site confidence

Call-site confidence: high

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

Patch: Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID [ Upstream
Commit: ba25efe15e8fd909884e113a86c6ccd07d88256e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ba25efe15e8fd909884e113a86c6ccd07d88256e

Changed files:
  net/bluetooth/iso.c
  net/bluetooth/bluetooth.h
  net/bluetooth/hci_core.h
  net/bluetooth/iso.h

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=ba25efe15e8fd909884e113a86c6ccd07d88256e

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

The original Linux kernel CVE announcement for CVE-2023-7356 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2023-7356

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:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.5

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