[CVE-2026-68406][LOW] wifi: cfg80211: validate PMSR FTM preamble range [ Upstream

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

CVE: CVE-2026-68406
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: cfg80211: validate PMSR FTM preamble range [ Upstream
Commit: 44ea65d779e2d23b2264fea6af2d0c666a3ec9fb
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=44ea65d779e2d23b2264fea6af2d0c666a3ec9fb
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68406
Analysis date: Mon, 10 Aug 2026 09:11:34 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
cfg80211 PMSR FTM request parsing accepted out-of-range nl80211 preamble values before a capability bit test, allowing a privileged or delegated local nl80211 caller to cause incorrect validation with at most low integrity or limited availability impact.

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

The original Linux kernel CVE announcement for CVE-2026-68406 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68406

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-2026-68406	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	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:L/A:L';*CWE-20;CWE-1284;CWE-682;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '4.4';DESCR 'cfg80211 PMSR FTM request parsing accepted a preamble value outside the nl80211 preamble enumeration before using it in a capability bit test. A local process able to submit the relevant nl80211 peer measurement request could provide an invalid value, which may cause incorrect capability validation or a warning class failure, but the patch does not indicate UAF, OOB write, arbitrary write, or information disclosure. For the CVSS the PR:L in the paranoid score reflects deployments where a reduced capability service account or delegated CAP_NET_ADMIN can submit nl80211 requests, while typical host level configuration still requires administrator privileges. The issue is not directly network reachable and cannot be triggered by WiFi traffic alone. Impact is low integrity policy bypass or limited availability impact, not privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	REMOTE OOB SIMPLEFIX TEST  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	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**

## 2. Signal breakdown

Conservative signals:

* Requires admin/root/CAP_NET_ADMIN in typical deployments: -2. Submitting nl80211 PMSR FTM requests is normally gated by WiFi management privileges or CAP_NET_ADMIN.
* Integrity impact plausible: +1. An out-of-range preamble value may affect capability validation logic.
* Broad/default/common subsystem: +1. cfg80211/nl80211 is a common WiFi control-plane subsystem, although this specific PMSR FTM path is narrower.
* Validation-only fix cap applies. The patch only tightens netlink attribute policy from unrestricted NLA_U32 to an enum range check and does not show UAF, OOB access, double free, stale pointer, refcount misuse, or arbitrary write.

Paranoid additional interpretation:

* Local reduced-privilege/delegated trigger concern: +1. In some deployments, WiFi control operations may be delegated to a service account, network manager component, container, or reduced-capability process rather than full host root.
* Limited availability concern: +1. The invalid value is used in a capability bit test, so a warning or invalid-state failure is possible, but no reliable crash is demonstrated.

Not awarded:

* No remote/network-triggerable score. This is a local nl80211 control-plane request, not WiFi packet parsing.
* No generic memory corruption score. The diff does not show UAF, OOB write, heap overwrite, type confusion, or refcount/lifetime corruption.
* No privilege escalation score. There is no concrete primitive for LPE.
* No strong DoS score. No panic, Oops, lockup, or reliable crash path is shown.

## 3. Reachability analysis

A local process capable of issuing the relevant nl80211 PMSR FTM request can trigger the affected parser path. In typical deployments this requires CAP_NET_ADMIN or equivalent WiFi management authority, so the conservative interpretation treats it as privileged. Namespace or service delegation can lower the practical privilege level, for example if a network management daemon exposes this operation to less trusted callers, but that is deployment-specific.

The path is not directly network reachable. It cannot be triggered by ordinary WiFi frames alone. The affected feature is also narrower than the general cfg80211/nl80211 interface because it is specific to PMSR FTM request parsing.

## 4. Severity interpretation

This behaves like a low-end Moderate or Low-like validation issue. The theoretical concern is incorrect capability validation or a warning-class failure from an invalid enum value used in a bit test. Realistic exploitation evidence is weak because the patch does not demonstrate memory corruption, disclosure, privilege escalation, or a reliable kernel crash.

The best practical handling is automatic or deferred triage unless additional external evidence shows a concrete crash or corruption primitive.

## 5. One-sentence report phrase

cfg80211 PMSR FTM request parsing accepted out-of-range nl80211 preamble values before a capability bit test, allowing a privileged or delegated local nl80211 caller to cause incorrect validation with at most low integrity or limited availability impact.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a validation-only nl80211 policy fix with no demonstrated memory corruption, no network-triggered path, no reliable DoS, and no plausible LPE primitive from the provided patch context.

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

Patch: wifi: cfg80211: validate PMSR FTM preamble range [ Upstream
Commit: 44ea65d779e2d23b2264fea6af2d0c666a3ec9fb
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=44ea65d779e2d23b2264fea6af2d0c666a3ec9fb

Changed files:
  net/wireless/nl80211.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=44ea65d779e2d23b2264fea6af2d0c666a3ec9fb

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

The original Linux kernel CVE announcement for CVE-2026-68406 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68406

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:H/UI:N/S:U/C:N/I:L/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS score: 4.4

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).