* [CVE-2026-98350][MODERATE REGULAR] wifi: brcmfmac: cyw: pass PMKID to firmware if present [ Upstream
@ 2026-10-10 14:37 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 14:37 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98350
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: brcmfmac: cyw: pass PMKID to firmware if present [ Upstream
Commit: c2cf589c7d546557ed60c43f2ec014279265dfbf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c2cf589c7d546557ed60c43f2ec014279265dfbf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98350
Analysis date: Sat, 10 Oct 2026 10:37:38 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98350 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98350
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: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98350 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98350 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 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:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L';*CWE-457;CWE-908;*CWE-200;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.6';DESCR 'The brcmfmac cyw external SAE authentication path uses an uninitialized auth_status structure and sends it to the wireless firmware. This can expose residual kernel stack bytes to firmware when the SSID is shorter than 32 bytes or when a PMKID is present. The missing PMKID copy can also make firmware cache an invalid PMKID and reject a later association request that supplies the correct value. The demonstrated impact is limited WiFi availability loss rather than a host wide kernel crash. For the CVSS the PR:N value is used in the paranoid score because a nearby malicious access point may influence SAE authentication and reassociation without holding an account on the target. User interaction is required because the device must attempt or automatically perform the affected wireless connection. Direct recovery of the leaked stack bytes by an attacker is not demonstrated, but the firmware boundary and adjacent network exposure justify manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 2) MAYBE REMOTE SIMPLEFIX LEAK NETWORK DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 1.
* Conservative score: 1. No floor or cap applied.
* Raw paranoid score: 3.
* Paranoid score: 3. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Conservative signals:
* +1 Availability impact realistic. An uninitialized or missing PMKID can be cached by firmware, causing a subsequent association request containing the correct PMKID to be rejected.
* No additional point for stack disclosure. Bytes are concretely transferred to firmware, but no attacker-readable return path is established.
Paranoid signals:
* +1 Availability impact realistic. The firmware can reject subsequent WiFi association.
* +1 Firmware-mediated external influence. A nearby access point participates in the external SAE authentication and reassociation sequence, although firmware mediation and client connection behavior remain prerequisites.
* +1 Confidentiality plausible. Residual kernel stack bytes are actually copied across the kernel-to-firmware interface. This is a concrete device-visible output, but attacker recovery of those bytes is unresolved.
Important non-awarded signals:
* No heap or slab OOB write, retry-accumulated overwrite, UAF, controlled reclaim, arbitrary write, or active-object lifetime corruption is present.
* No direct remote reachability point was awarded because traffic is mediated by the wireless firmware and external SAE state machine.
* No strong DoS point was awarded because the demonstrated result is a WiFi association failure, not a kernel crash or host-wide outage.
* No integrity point was awarded. The incorrect PMKID changes firmware connection state but does not establish unauthorized modification of protected host state.
* No authorization bypass or protected-resource access is established. B4-PENDING does not apply.
* B3-PENDING does not apply because no shared or file-backed storage is modified.
* B5-R does not apply because there is no OOB write or retry-accumulated offset.
3. Reachability analysis
The affected operation is the brcmfmac CYW external SAE authentication callback. A nearby access point can participate in the authentication and reassociation sequence, but the supplied evidence does not prove that the access point alone controls invocation, stack contents, or retrieval of bytes delivered to firmware.
A local network-management component may initiate the connection and provide the external authentication result. The supplied context does not establish whether an ordinary user, a privileged NetworkManager-like service, or host administration is required for the complete trigger. Therefore HostAdminRequired remains UNKNOWN rather than being assumed either YES or NO.
No user-namespace or network-namespace capability path is shown, so NamespaceScopedPrivilege is UNKNOWN. The vulnerable path requires compatible Broadcom CYW hardware, brcmfmac external SAE support, and an attempted WiFi connection. It is not a race and does not depend on a narrow timing window.
4. Primitive and severity interpretation
The exact defect is use of a partially uninitialized stack structure as a firmware command. Initializing auth_status only through selected field assignments leaves residual stack bytes in fields not explicitly written. The separate PMKID omission causes firmware to cache an invalid value and reject a later association.
This is not an OOB access or memory corruption inside kernel storage. The destination is a firmware command buffer with fixed structure semantics. No post-lifetime object use, repeated release, shared-backing modification, or authorization decision bypass exists.
PrimitiveClass is CLASS_C because the demonstrated security-relevant behavior is constrained information transfer to firmware plus invalid firmware authentication state and device-level availability loss. The demonstrated consequence is failed WiFi reassociation. A speculative consequence is recovery of residual stack bytes through firmware behavior or diagnostics, but no such read-back path is supplied.
ImportantCandidate is NO because there is no established Important-preserving corruption, ownership, lifetime, authorization, or cross-boundary primitive. AutoDowngradeAllowed is YES because the unresolved firmware observability question does not establish meaningful exploitation leverage. Operational severity is Low-like to borderline Moderate.
5. One-sentence report phrase
An uninitialized brcmfmac external SAE request can expose residual kernel stack bytes to wireless firmware and cache an invalid PMKID, causing later WiFi association failure without demonstrating host memory corruption or privilege escalation.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Confirm whether affected firmware exposes the residual command bytes through events, diagnostics, crash dumps, or wireless responses observable by a nearby attacker. Without such a path, the practical impact is limited to connection failure.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: brcmfmac: cyw: pass PMKID to firmware if present [ Upstream
Commit: c2cf589c7d546557ed60c43f2ec014279265dfbf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c2cf589c7d546557ed60c43f2ec014279265dfbf
Changed files:
drivers/net/wireless/broadcom/brcm80211/brcmfmac/cyw/core.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=c2cf589c7d546557ed60c43f2ec014279265dfbf
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98350 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98350
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:L/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L
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: 1
Paranoid ActionableScore: 3
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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