[CVE-2026-68304][LOW] wifi: brcmfmac: fix 802.1X-SHA256 call trace warning [ Upstream

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

CVE: CVE-2026-68304
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: brcmfmac: fix 802.1X-SHA256 call trace warning [ Upstream
Commit: 137e4710da626290495b174e2eb1d5e889a4b165
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=137e4710da626290495b174e2eb1d5e889a4b165
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68304
Analysis date: Mon, 10 Aug 2026 09:30:39 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like. Autoclose candidate
Manual review required: NO

Summary:
A brcmfmac state handling bug in the 802.1X-SHA256 firmware supplicant offload path can trigger a WARN in brcmf_cfg80211_set_pmk during WiFi connection setup, with practical impact limited to warning noise or DoS on panic_on_warn systems.

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

The original Linux kernel CVE announcement for CVE-2026-68304 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68304

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: LOW
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-2026-68304	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-703;CWE-754;CWE-665;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A WARN in brcmfmac can be triggered when an 802.1X-SHA256 connection uses firmware supplicant offload but the driver does not mark this authentication mode as BRCMF_PROFILE_FWSUP_1X before brcmf_cfg80211_set_pmk() is called. The visible effect is a call trace warning from the nl80211_set_pmk path on systems using affected Broadcom WiFi hardware and this authentication mode. For the CVSS the PR:L is used because a local user or local network management process must be able to initiate or configure the WiFi connection or PMK setup. The issue is not directly network reachable through packet processing, although a malicious or misconfigured access point may be involved if the client is already allowed to connect to that 802.1X network. Impact is denial of service at most, mainly warning noise or a crash only on systems configured to panic on WARN.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Autoclose candidate (with actual score 1)	YES	REMOTE NETWORK HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like. Autoclose candidate**

## 2. Signal breakdown

Conservative signals:

* WARN_ON / state validation concern: +1
  The patch fixes incorrect authentication mode handling that leads to a WARN/call trace in `brcmf_cfg80211_set_pmk()`.
* Requires privileged network management in typical deployments: -2
  Direct nl80211 WiFi configuration paths are normally driven by privileged components such as wpa_supplicant or NetworkManager with appropriate permissions.
* Hardware and mode specific exposure: -1
  Requires Broadcom brcmfmac hardware and the 802.1X-SHA256 firmware supplicant offload path.

Conservative result is floored at 0.

Paranoid signals:

* Local user assisted trigger: +1
  On desktop systems a non-root user may be able to initiate a WiFi connection through a privileged network manager.
* Firmware or AP mediated external influence: +1
  A malicious or misconfigured AP may be part of the practical trigger if the client attempts to connect using 802.1X-SHA256.
* WARN may become DoS on panic_on_warn systems: +1
  The visible failure is a WARN, but some hardened/debug systems treat WARN as fatal.
* Hardware and mode specific exposure: -1
  The affected path is not generic WiFi processing and depends on brcmfmac plus this authentication mode.

Paranoid result: 2.

No points for memory corruption, UAF, OOB, privilege escalation, confidentiality impact, or integrity impact. The patch is a one-line logic/state fix and does not show a concrete corruption primitive.

## 3. Reachability analysis

The bug is triggered through WiFi connection setup and PMK configuration, not through ordinary packet receive processing. In typical deployments, the direct kernel interface is reached by privileged networking software, so this is not a broad unprivileged kernel attack surface. A local desktop user may indirectly trigger the path via NetworkManager policy, which is why the paranoid score includes local-user-assisted reachability.

Namespaces and containers do not materially increase exposure unless they are delegated real WiFi device control or CAP_NET_ADMIN over the relevant interface. The affected configuration also requires Broadcom brcmfmac hardware and 802.1X-SHA256 firmware supplicant offload, so it is not a default/common path on all Linux systems.

Call-site confidence: high. The provided stack trace and changed condition directly show the warning path.

## 4. Severity interpretation

This behaves like a low-end Moderate or Low-like correctness issue, not an Important-class vulnerability. The realistic impact is warning noise or connection failure, with possible DoS only on systems configured to panic on WARN.

Theoretical impact beyond DoS is not supported. There is no evidence of UAF, stale pointer reuse, attacker-controlled overwrite, type confusion, information disclosure, or privilege escalation.

## 5. One-sentence report phrase

A brcmfmac state handling bug in the 802.1X-SHA256 firmware supplicant offload path can trigger a WARN in brcmf_cfg80211_set_pmk during WiFi connection setup, with practical impact limited to warning noise or DoS on panic_on_warn systems.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a hardware and authentication-mode specific WARN-only logic fix with no demonstrated memory corruption, no security-boundary bypass, no confidentiality or integrity primitive, and no realistic Important-class escalation path.

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

Patch: wifi: brcmfmac: fix 802.1X-SHA256 call trace warning [ Upstream
Commit: 137e4710da626290495b174e2eb1d5e889a4b165
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=137e4710da626290495b174e2eb1d5e889a4b165

Changed files:
  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.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=137e4710da626290495b174e2eb1d5e889a4b165

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

The original Linux kernel CVE announcement for CVE-2026-68304 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68304

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:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 0
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).