[CVE-2026-93271][MODERATE REGULAR] wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate [ Upstream

[CVE-2026-93271][MODERATE REGULAR] wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate [ Upstream

[AL-KERNEL]

CVE: CVE-2026-93271
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate [ Upstream
Commit: 6ad04c3e2ec54bf5ec72c81afdd66318a116c539
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6ad04c3e2ec54bf5ec72c81afdd66318a116c539
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93271
Analysis date: Thu, 24 Sep 2026 13:58:58 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-93271 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93271

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: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-93271	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-93271 CHECK WITH IMPACT FROM ORIG NN MODERATE	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:L';*CWE-20;CWE-1284;CWE-703;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.3';DESCR 'An ath11k WiFi receive path can report an out of range HT VHT or HE MCS value in rx status metadata. The invalid rate metadata reaches mac80211, triggers a rate sanity warning, and causes an otherwise decodable frame to be dropped. The issue is adjacent network reachable because an attacker must be within WiFi radio range of an affected ath11k device. For the CVSS the paranoid score uses PR:N because no local account or local code execution is needed once the attacker can send relevant wireless traffic. Impact is limited to availability degradation through dropped frames and warning generation. The patch context does not show memory corruption, information disclosure, integrity loss, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	REMOTE OOB NETWORK HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

The conservative score has no positive security primitive. The paranoid score adds one point for firmware-mediated external wireless input because the affected RX metadata is derived through ath11k hardware and firmware processing of received WiFi frames.

2. Signal breakdown

* +1 paranoid only. Firmware-mediated external influence. The affected rate MCS metadata is received through the ath11k RX hardware and firmware path and can reach mac80211 while processing wireless traffic.
* +0. No memory corruption primitive is established. The patch only caps an invalid rate value and initializes encoding metadata before passing the frame to mac80211.
* +0. No UAF, stale pointer, double release, refcount misuse, OOB access, arbitrary write, controlled reclaim, or type confusion is established.
* +0. No confidentiality impact is established. The invalid rate metadata is not copied to an attacker-visible disclosure channel.
* +0. No integrity impact is established. The patch does not show modification of protected kernel state, persistent storage, credentials, policy, or another principals data.
* +0. Reliable kernel crash or strong DoS is not established. The observed behavior is a mac80211 WARNING and dropping of the individual frame.
* +0. Additional availability impact is not awarded. Loss of frames carrying an out-of-range reported MCS is limited and does not establish host-wide or persistent network unavailability.
* +0. Direct remote network reachability is not awarded. This is WiFi radio-adjacent input processed through device hardware and firmware, not ordinary routable network access.
* +0. No privilege escalation or exploitation leverage is established.
* +0. No special hardware penalty is applied. ath11k Qualcomm WiFi hardware is hardware-specific, but the issue does not involve a dangerous driver lifetime or DMA primitive.

3. Reachability analysis

The possible attacker model is a nearby wireless sender within radio range of an affected ath11k device. No local account, local code execution, host administrative capability, namespace capability, or prior attacker-controlled kernel configuration is required if a transmitted frame can cause the device or firmware to report an out-of-range MCS value.

However, the supplied patch does not establish that an attacker can reliably force the ath11k firmware or hardware to generate the anomalous descriptor value. The report states that ath11k can receive such frames, but the MCS value reaching the driver is mediated by device firmware and RX descriptor handling. This is therefore treated as firmware-mediated external influence rather than a proven directly attacker-controlled packet primitive.

No namespace-scoped privilege is involved. No special sysctl, boot option, privileged setup, or unusual device topology is identified beyond use of an affected ath11k WiFi adapter and wireless reception.

4. Primitive and severity interpretation

The exact defect is invalid RX rate metadata handling. For HT, VHT, and HE frames, an MCS value above the mac80211 representable range could leave rate_idx out of range. For HE frames, encoding could remain RX_ENC_LEGACY instead of RX_ENC_HE. mac80211 detects the inconsistent rate state, emits a WARNING, and drops the frame.

This is not an active lifetime issue, fixed stale storage issue, cleanup/destructor issue, ownership violation, authorization bypass, or memory-corruption primitive. No concrete repeated release or refcount operation exists.

PrimitiveClass is NONE because the demonstrated effect is limited to incorrect metadata, a warning, and loss of an otherwise decodable frame. The patch-supported practical consequence is limited availability degradation for affected frames and potentially warning log noise.

ImportantCandidate is NO because there is no unresolved kernel corruption, security-boundary bypass, lifetime primitive, information disclosure, integrity impact, or privilege-escalation mechanism. AutoDowngradeAllowed is YES because the patch establishes a bounded validation and metadata-consistency defect rather than a meaningful unresolved exploitation primitive.

5. One-sentence report phrase

An ath11k RX metadata validation issue can cause mac80211 to warn and drop wireless frames reported with an out-of-range HT VHT or HE MCS value, resulting in limited WiFi availability degradation without demonstrated memory corruption or privilege escalation.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The issue is externally reachable from WiFi radio traffic, but manual review should only verify whether attacker-controlled over-the-air frames can reliably induce the anomalous firmware-reported MCS value. Current patch evidence supports frame loss and warnings only.

7. Call-site confidence

Call-site confidence: medium

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

Patch: wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate [ Upstream
Commit: 6ad04c3e2ec54bf5ec72c81afdd66318a116c539
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6ad04c3e2ec54bf5ec72c81afdd66318a116c539

Changed files:
  net/mac80211/rx.c
  drivers/net/wireless/ath/ath11k/dp_rx.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=6ad04c3e2ec54bf5ec72c81afdd66318a116c539

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

The original Linux kernel CVE announcement for CVE-2026-93271 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93271

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:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 4.3

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: 0
  Paranoid ActionableScore: 1

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).