* [CVE-2026-98702][MODERATE 7.0] wifi: mac80211: reject invalid 320 MHz CSA bandwidth
@ 2026-10-19 8:26 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-19 8:26 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98702
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: wifi: mac80211: reject invalid 320 MHz CSA bandwidth
Commit: cf0ddacce173890407ed3fa50c8ea9b3c0cc0e16
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf0ddacce173890407ed3fa50c8ea9b3c0cc0e16
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98702
Analysis date: Mon, 19 Oct 2026 04:26:10 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
A nearby wireless attacker may send an invalid 320 MHz CSA indication on a non 6 GHz link, causing an uninitialized channel-width read and, when panic_on_warn is enabled, a kernel panic and denial of service.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98702 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98702
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-98702 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98702 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-457;*CWE-20;CWE-754;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.5';DESCR 'An invalid 320 MHz bandwidth indication in a received CSA frame on a non 6 GHz WiFi link can leave vht_operation.chan_width uninitialized before it is read by ieee80211_chandef_vht_oper(). With panic_on_warn enabled the WARN_ON in this path can immediately panic the kernel and cause a denial of service. For the CVSS the PR:N value is used because no account or privileges on the target are required to transmit the wireless frame. The attack is adjacent rather than general network remote because the attacker must be within radio reach and the target must process the crafted CSA frame in a suitable link state. The demonstrated impact is availability loss only. There is no supported UAF OOB access information disclosure or write primitive that would justify confidentiality or integrity impact. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 6.5 and the production ActionableScore returned 4 with recommendation Borderline / manual review recommended. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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 has no review artifact for this run. The independent weaker Aegis shadow evaluated CVSS 5.3 and ActionableScore 2 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) MAYBE REMOTE DANGER SIMPLEFIX KPANIC - - checked
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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
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: 4
* Conservative score: 4
* Raw paranoid score: 4
* Paranoid score: 4
* No floor or cap was applied.
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
Positive signals:
* +2 Directly traffic-triggerable wireless path. An attacker-influenced CSA frame reaches the vulnerable validator without requiring an account or privileges on the target.
* +1 Reliable kernel panic under the explicitly documented `panic_on_warn` configuration.
* +1 Broadly deployed exposure. mac80211 station operation and CSA processing are realistic WiFi functionality, although successful frame injection depends on link state and management-frame protections.
Non-awarded signals:
* No UAF, OOB access, write primitive, controlled corruption, or lifetime violation is established.
* The uninitialized value is read internally, but no disclosure or subsequent memory write is demonstrated.
* No C or I impact is awarded.
* No authorization decision or protected-resource access is involved.
* No additional availability point is awarded for the same kernel panic.
* B5-R does not apply because there is no retry-accumulated heap OOB write.
* B3-PENDING does not apply because there is no shared-backing write.
* V33 and V34 do not apply because no active structured-state write or checksum metadata corruption exists.
3. Reachability analysis
A nearby wireless attacker can transmit or spoof a CSA frame containing a 320 MHz bandwidth indication for a non-6 GHz link. No target-side UID, capability, namespace privilege, or host-administrator access is required.
The target must be using an affected mac80211 station path and must accept the crafted management frame in the relevant connection state. Management Frame Protection, source validation, association state, driver behavior, and radio proximity can limit practical reachability. A fatal host-wide consequence additionally requires `panic_on_warn` to be enabled.
There is no race. No unusual physical device beyond ordinary compatible WiFi hardware is indicated.
4. Primitive and severity interpretation
The exact primitive is a read of the uninitialized scalar field `vht_operation.chan_width` after the unsupported 320 MHz case emits `WARN_ON` and continues. With `panic_on_warn`, execution terminates at the warning before the uninitialized value can produce a separate consequence.
This is not an active-object UAF, stale-storage use, OOB operation, or repeated lifetime mutation. It is CLASS_C because the supported security consequence is an externally triggerable kernel panic and denial of service.
ImportantCandidate is NO because no independently useful corruption, disclosure, integrity modification, authorization bypass, or privilege-escalation primitive is established. AutoDowngradeAllowed is YES because the demonstrated behavior remains crash-only, although manual review is recommended to verify real frame acceptance and deployment exposure.
5. One-sentence report phrase
A nearby wireless attacker may send an invalid 320 MHz CSA indication on a non 6 GHz link, causing an uninitialized channel-width read and, when panic_on_warn is enabled, a kernel panic and denial of service.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Verify whether crafted CSA frames are accepted from an unauthenticated or spoofed transmitter under the affected association and Management Frame Protection configurations, and whether `panic_on_warn` is enabled in the evaluated product.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: mac80211: reject invalid 320 MHz CSA bandwidth
Commit: cf0ddacce173890407ed3fa50c8ea9b3c0cc0e16
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf0ddacce173890407ed3fa50c8ea9b3c0cc0e16
Commit description:
The HT/VHT channel definition validator can receive a 320 MHz
bandwidth indication from a received CSA frame on a non-6 GHz link.
It warns for this unsupported width but continues with an uninitialized
vht_operation.chan_width, which is then read by
ieee80211_chandef_vht_oper(). With panic_on_warn enabled, this lets a
received frame panic the kernel.
Reject the channel definition before entering the VHT operation
conversion. This preserves the existing CSA fallback while avoiding
both the warning and the uninitialized read.
Fixes: 21c3f8f ("wifi: mac80211: refactor STA CSA parsing flows")
Cc: [email protected]
Reported-by: Vega <[email protected]>
Assisted-by: LLM
Signed-off-by: Ruide Cao <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
Link: https://patch.msgid.link/bd68e360e06135c750397cb6be003a01a834a179.1787222001.git.vega.cover-letter@nebusec.ai
Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
net/mac80211/spectmgmt.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=cf0ddacce173890407ed3fa50c8ea9b3c0cc0e16
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98702 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98702
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:H
The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 6.5
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: 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: YES
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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