* [CVE-2026-98340][MODERATE REGULAR] wifi: cfg80211: only group hidden BSSes with beacon entries [ Upstream
@ 2026-10-10 11:47 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 11:47 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98340
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: cfg80211: only group hidden BSSes with beacon entries [ Upstream
Commit: 4cd6a518ce7527284bbc9baab5fa2453a7d477c2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4cd6a518ce7527284bbc9baab5fa2453a7d477c2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98340
Analysis date: Sat, 10 Oct 2026 07:47:59 -0400
ActionableScore: 4
ActionableScore lower bound: 3
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-2026-98340 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98340
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-2026-98340 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98340 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=MODERATE RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both MODERATE) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-20;*CWE-664;CWE-670;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'cfg80211 can incorrectly group two probe response BSS entries even when the selected hidden entry has no beacon data. A later hidden SSID beacon for the same BSSID and channel can make cfg80211_combine_bsses encounter entries that are already grouped and trigger WARN_ON_ONCE checks for hidden_beacon_bss and hidden_list. A nearby wireless attacker may be able to influence this state by transmitting a specific sequence of management frames while the target is scanning, so AV:A and AC:H are appropriate. For the CVSS the PR:N value is used because no authenticated local user or target side privilege is required when crafted wireless frames can reach the scanning interface. The demonstrated effect is a warning and limited availability degradation on normal systems. On systems configured with panic_on_warn the same condition may cause a kernel panic and a stronger denial of service. No UAF, OOB access, information disclosure, or write primitive is established by the affected path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) MAYBE REMOTE DANGER SYZBOT DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=4
ActionableScoreLower=3
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: 3
* Conservative score: 3. No floor or cap applied.
* Raw paranoid score: 4
* Paranoid score: 4. No floor or cap applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Conservative signals:
* +2 Directly network-triggerable. A nearby wireless transmitter can influence cfg80211 input by sending the required probe-response and hidden-beacon sequence while the interface is scanning.
* +1 Broadly exercised exposure. cfg80211 BSS discovery and WiFi scanning are common operational paths.
* +0 WARN_ON_ONCE. The demonstrated result is an invariant warning, not memory corruption or a fatal host failure.
Paranoid additional signal:
* +1 Conditional strong DoS. On a system configured with panic_on_warn, the demonstrated WARN_ON_ONCE can become a kernel panic. This is configuration-dependent and is not included in the conservative score.
Not awarded:
* No UAF, OOB read, OOB write, stale lifetime use, arbitrary write, controlled reclaim, or shared-backing modification is established.
* No confidentiality, integrity, authorization-bypass, privilege-escalation, or protected-resource impact is established.
* B5-R does not apply because there is no retry-accumulated heap OOB write or later consumption of corrupted descriptors.
* B3-PENDING does not apply because there is no write to shared or file-backed storage.
* B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW.
* No timing penalty is applied. The trigger requires an ordered frame and cache-state sequence, but no narrow or uncontrollable race is established.
* No additional availability point is awarded for the same conditional panic.
3. Reachability analysis
The plausible attacker is a nearby wireless actor capable of transmitting management frames with selected BSSID, SSID, channel, and ordering. No local account, host UID 0, capability, namespace privilege, or host-administrator access is required for over-the-air frame transmission.
The target must have a compatible wireless interface and be scanning so that the crafted probe responses and later hidden-SSID beacon enter the cfg80211 BSS cache. This is an operational prerequisite rather than attacker-controlled privileged setup. No unusual hardware or rare kernel configuration is required beyond ordinary WiFi support. Fatal impact additionally requires panic_on_warn or an equivalent fatal-warning policy configured by the administrator.
4. Primitive and severity interpretation
The exact primitive is an invalid BSS grouping state. A probe-response entry without beacon IEs can incorrectly become the hidden beacon parent of another probe-response entry. A later beacon causes cfg80211_combine_bsses to encounter entries that are already grouped, violating hidden_beacon_bss and hidden_list invariants and triggering WARN_ON_ONCE.
This is CLASS_C because the demonstrated behavior is invalid-state detection and warning-driven DoS potential. It is not an active-object UAF, repeated release, OOB operation, or independently useful corruption primitive. The patch-supported practical consequence is a warning. Kernel panic is a configuration-dependent worst case. Exploitation leverage beyond denial of service is not established.
ImportantCandidate is NO because no Important-preserving corruption, ownership, lifetime, semantic-reinterpretation, or authorization primitive exists. AutoDowngradeAllowed is YES because the issue remains a constrained warning or conditional crash case without unresolved non-crash exploitation leverage.
5. One-sentence report phrase
A nearby wireless attacker may create an invalid cfg80211 hidden BSS grouping through an ordered probe-response and beacon sequence, triggering WARN_ON_ONCE and potentially a kernel panic on systems configured with panic_on_warn.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Confirm whether over-the-air reproduction is practical with the affected driver and whether the evaluated product enables panic_on_warn, but no evidence currently supports Important-class memory corruption or privilege escalation.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: cfg80211: only group hidden BSSes with beacon entries [ Upstream
Commit: 4cd6a518ce7527284bbc9baab5fa2453a7d477c2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4cd6a518ce7527284bbc9baab5fa2453a7d477c2
Changed files:
net/wireless/scan.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=4cd6a518ce7527284bbc9baab5fa2453a7d477c2
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98340 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98340
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:N/I:N/A:L
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 5.3
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: 4
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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