[CVE-2026-43110][MODERATE 7.0] wifi: brcmfmac: validate bsscfg indices in IF events [ Upstream

[CVE-2026-43110][MODERATE 7.0] wifi: brcmfmac: validate bsscfg indices in IF events [ Upstream

[AL-KERNEL]

CVE: CVE-2026-43110
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: brcmfmac: validate bsscfg indices in IF events [ Upstream
Commit: 3ec7437e9d11374105c2c4e47ae671537729d7e6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ec7437e9d11374105c2c4e47ae671537729d7e6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43110
Analysis date: Tue, 09 Jun 2026 18:12:33 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum**:: Actionable Moderate at minimum, not auto-close.
Manual review required: YES

Summary:
A firmware-provided `bsscfgidx` in brcmfmac IF events was used as an unchecked index into `drvr->iflist[]`, allowing firmware-mediated out-of-bounds interface pointer access that can plausibly crash the kernel and may require manual review for driver-state corruption risk.

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

The original Linux kernel CVE announcement for CVE-2026-43110 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43110

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.

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

CVE-2026-43110	MODERATE	CHECK	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-129;CWE-125;*CWE-787;**CWE-476;Other CVSS 'AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'brcmfmac handles firmware IF events and validated ifidx, but it used the raw firmware provided bsscfgidx as an index into drvr iflist without a matching range check. An invalid bsscfgidx can cause out-of-bounds access to the interface pointer array and may lead to an invalid pointer dereference, kernel crash, or driver state corruption depending on the IF event action and surrounding memory layout. For the CVSS the PR:N is used in the paranoid score because the attacker does not need a local account on the victim if the event can be influenced from the WiFi environment or a malicious firmware/device path. The issue is best treated as adjacent network reachable rather than Internet reachable because practical triggering would usually require proximity to the WiFi device, a malicious AP, compromised firmware, or a similar local radio/device context. Impact is at least denial of service and in the paranoid interpretation may include confidentiality and integrity impact because this is an unchecked firmware controlled array index in kernel driver state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE SIMPLEFIX NETWORK  INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: Actionable Moderate at minimum, not auto-close.

## 2. Signal breakdown

Conservative signals:

* Firmware-mediated external influence: +1. The bad index is firmware-provided through a brcmfmac IF event, not a direct syscall or packet parser input.
* Memory corruption, Weak/indirect corruption candidate: +1. The bug is an unchecked firmware-controlled array index into `drvr->iflist[]`, producing possible bogus object pointer selection.
* Reliable kernel crash / strong DoS: +1. A bogus `ifp` pointer can plausibly lead to invalid pointer dereference in the IF event path.
* Hard or unreliable trigger conditions: -1. Practical triggering likely depends on firmware behavior, malicious or compromised device state, or WiFi-environment-mediated event generation.
* Broad/common deployment exposure: +1. brcmfmac is a real-world Broadcom WiFi driver used on laptops and embedded devices, though only on affected hardware.

Paranoid additional signals:

* Weak LPE concern: +1. The primitive is not a demonstrated arbitrary write, but bogus interface pointer selection inside a kernel WiFi driver is enough to require manual review.
* Privileged kernel/device-management corruption path: +1. The corruption candidate occurs in trusted driver state fed by firmware events.
* Constrained/uncertain primitive: -1. No attacker-controlled payload, reclaim primitive, function pointer control, or write target is shown in the patch.

Net paranoid score: 5.

## 3. Reachability analysis

The most realistic trigger source is a malformed or unexpected firmware IF event with `bsscfgidx >= BRCMF_MAX_IFS`. This is not Internet-reachable and should not be treated like a normal remote network parser bug. It is better modeled as adjacent or firmware-mediated exposure, where triggering may require proximity to the WiFi device, a malicious AP influencing firmware behavior, compromised firmware, or a device/driver state that causes such an event.

No local Linux user account is necessarily required if the event can be influenced externally through the WiFi/firmware path. Namespaces and containers are not the main access-control boundary here. The path is enabled only when the brcmfmac driver is loaded on affected Broadcom WiFi hardware.

## 4. Severity interpretation

This is more than an ordinary low-risk validation cleanup because the unchecked value indexes a kernel pointer array. The realistic demonstrated impact is likely DoS through invalid pointer dereference or driver crash. The theoretical risk is higher because bogus object pointer selection in a kernel WiFi driver may become memory corruption depending on subsequent IF event handling, but the patch does not show a strong primitive such as attacker-controlled overwrite, UAF reclaim, callback hijack, or arbitrary write.

Main interpretation: Borderline to Actionable Moderate.
Paranoid interpretation: Actionable Moderate at minimum and should not be auto-closed without review.

## 5. One-sentence report phrase

A firmware-provided `bsscfgidx` in brcmfmac IF events was used as an unchecked index into `drvr->iflist[]`, allowing firmware-mediated out-of-bounds interface pointer access that can plausibly crash the kernel and may require manual review for driver-state corruption risk.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: unchecked firmware-controlled indexing into a kernel pointer array is a memory-corruption candidate, even though the currently demonstrated impact is mainly DoS and the trigger path is firmware/adjacent rather than directly network-reachable.

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

Patch: wifi: brcmfmac: validate bsscfg indices in IF events [ Upstream
Commit: 3ec7437e9d11374105c2c4e47ae671537729d7e6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ec7437e9d11374105c2c4e47ae671537729d7e6

Changed files:
  drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.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=3ec7437e9d11374105c2c4e47ae671537729d7e6

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

The original Linux kernel CVE announcement for CVE-2026-43110 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43110

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:R/S:U/C:N/I:N/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: 3
  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: MODERATE
KPANIC detected for this report: NO
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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).