[CVE-2026-90407][MODERATE REGULAR] wifi: ath11k: fix overreads in ath11k_wmi_process_csa_switch_count_event() [ Upstream

[CVE-2026-90407][MODERATE REGULAR] wifi: ath11k: fix overreads in ath11k_wmi_process_csa_switch_count_event() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90407
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: ath11k: fix overreads in ath11k_wmi_process_csa_switch_count_event() [ Upstream
Commit: f760b7d7e43584d2fa9bffcec1a04e502609f827
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f760b7d7e43584d2fa9bffcec1a04e502609f827
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90407
Analysis date: Thu, 17 Sep 2026 17:09:03 -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-2026-90407 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90407

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-2026-90407	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-90407 CHECK WITH IMPACT FROM ORIG NN 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:L/I:N/A:H';CWE-126;CWE-125;*CWE-20;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.9';DESCR 'A malformed or inconsistent ath11k WMI CSA switch count event can cause an out of bounds read because the fixed event TLV had no minimum length policy and num_vdevs from firmware was used as the loop bound for vdev_ids without checking the TLV payload length. This is not an Internet routable TCP service. Practical exposure is limited to systems with affected ath11k WiFi hardware and a reachable adjacent wireless condition that can influence the CSA handling path or to a compromised firmware/device event path. For the CVSS the PR:N is used because an adjacent attacker would not need a local account on the victim if the event can be induced through WiFi behavior. AC:H is used because reliable triggering depends on a specific firmware event path and device state. Impact is mainly denial of service or KASAN detectable kernel overread, with possible limited confidentiality concern from an out of bounds read but no evidence of an arbitrary write or direct privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 2)	YES	REMOTE OOB NETWORK HARDWARE LINUS TEST  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	NO	NO	checked

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

ActionableScore=3
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

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 Limited read-only OOB primitive. The patch establishes that missing TLV minimum length validation and unchecked firmware supplied num_vdevs can make the driver read beyond the vdev_ids TLV payload.
* No negative privilege penalty. Host-admin-equivalent triggering is not positively established.
* No hardware rarity penalty. ath11k is hardware-specific, but the supplied evidence does not show rare or physical-only access requirements.

Paranoid additional signals:

* +1 Firmware-mediated external influence. The event originates from firmware and may be influenced by wireless CSA related behavior, but firmware/device mediation is material.
* +1 Plausible kernel crash or strong DoS. A kernel OOB read in a driver event handler can plausibly produce a fault or KASAN-detected overread, although a deterministic panic is not directly demonstrated.

Non-awarded signals:

* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Real UAF not established.
* Concrete repeated release/refcount mutation not present.
* Confidentiality not awarded because no user-visible, network-visible, or device-visible disclosure path is shown.
* Integrity not awarded because the primitive is read-only.
* Direct remote reachability not awarded because traffic does not directly reach the vulnerable code without firmware/device mediation.
* Strong LPE or Important-grade exploitation leverage not awarded.

3. Reachability analysis

The vulnerable path is in ath11k WMI CSA switch count event processing. The immediate input is a firmware generated WMI TLV event, not a directly parsed Internet packet or ordinary local syscall input.

A nearby wireless actor might influence CSA related behavior that leads firmware to emit such an event, but the supplied evidence does not prove the complete trigger chain from attacker controlled WiFi frames to the malformed WMI payload. A compromised or faulty firmware/device path could also trigger it.

HostAdminRequired is UNKNOWN because the evidence does not prove that host administrator privilege is required, but also does not fully prove ordinary below-host-admin reachability for the complete malformed-event path.

NamespaceScopedPrivilege is NO because namespaces are not relevant to this driver WMI event path.

Prior setup requires affected ath11k hardware and a loaded driver. No special boot option or rare configuration is established. No race or timing requirement is present.

4. Primitive and severity interpretation

The exact primitive is an out-of-bounds read from a parsed WMI TLV payload. The first issue is absence of a policy entry for WMI_TAG_PDEV_CSA_SWITCH_COUNT_STATUS_EVENT, so the fixed-size event structure minimum length was not enforced. The second issue is using firmware supplied num_vdevs as the loop bound over vdev_ids without checking that the TLV payload contains that many u32 entries.

This is not an active structured-object UAF and not fixed stale storage. It is a read-only bounds validation bug in a firmware event handler. There is no cleanup/destructor stale use and no concrete repeated release/refcount operation.

PrimitiveClass is CLASS_C because the demonstrated behavior is an invalid read / overread with likely DoS potential, but no independently useful corruption, disclosure, ownership, or authorization primitive is established.

ImportantCandidate is NO because the patch supports OOB read and possible crash, but not controlled memory corruption, arbitrary readback, privilege escalation, or a security-boundary bypass.

AutoDowngradeAllowed is YES because this is a constrained read-only OOB issue without UAF, write primitive, disclosure path, or unresolved strong exploitation leverage. Manual review is still recommended due to the adjacent wireless and firmware-mediated attack surface.

Likely operational severity is low-to-moderate / borderline. It should not be treated as a strong Important candidate without additional evidence that wireless attackers can reliably induce malformed firmware events or that the overread leaks data externally.

5. One-sentence report phrase

An ath11k WMI CSA switch count event can cause a firmware mediated out of bounds read because the event TLV lacked minimum length validation and num_vdevs was not bounded by the vdev_ids payload length, with practical impact mainly limited to possible kernel crash or diagnostic overread.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the primitive is limited, but the wireless adjacent firmware-mediated path should be checked manually to confirm whether an external attacker can realistically induce the malformed CSA event.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: ath11k: fix overreads in ath11k_wmi_process_csa_switch_count_event() [ Upstream
Commit: f760b7d7e43584d2fa9bffcec1a04e502609f827
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f760b7d7e43584d2fa9bffcec1a04e502609f827

Changed files:
  drivers/net/wireless/ath/ath11k/wmi.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=f760b7d7e43584d2fa9bffcec1a04e502609f827

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

The original Linux kernel CVE announcement for CVE-2026-90407 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90407

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:L/I:N/A:H
  The Best / paranoid CVSS score: 5.9

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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).