[CVE-2026-46166][IMPORTANT] wifi: mac80211: use safe list iteration in radar detect work

[CVE-2026-46166][IMPORTANT] wifi: mac80211: use safe list iteration in radar detect work

[AL-KERNEL]

CVE: CVE-2026-46166
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: wifi: mac80211: use safe list iteration in radar detect work
Commit: 887ece6c23b49d02a6678e7a8d5ad213d75883ce
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=887ece6c23b49d02a6678e7a8d5ad213d75883ce
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46166
Analysis date: Thu, 28 May 2026 11:22:38 -0400
ActionableScore: 8
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
mac80211 DFS radar detection work used unsafe list iteration while CAC cancellation could free the current channel context, creating a slab use-after-free that may be RF-adjacent triggerable in DFS configurations.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-46166 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46166

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: IMPORTANT
Manual review required: YES

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-2026-46166	IMPORTANT	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;*CWE-664;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'mac80211 radar detection work iterated chanctx_list unsafely while ieee80211_dfs_cac_cancel could remove and free the current channel context. This can leave the iterator using a freed chanctx and cause a slab use-after-free in the DFS radar handling path. For the CVSS the PR:N is used for the paranoid score because an attacker in radio range may trigger radar detection once the device is already operating on a DFS channel, without local privileges on the victim. The issue is not Internet reachable and requires a specific Wi-Fi DFS and channel context state. Impact is at least denial of service through kernel crash, and worst case may allow confidentiality or integrity impact because this is kernel heap lifetime corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 8) 	MAYBE	REMOTE DANGER UAF KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=8
ActionableScoreLower=6

## 1. ActionableScore

* Conservative score: 6
* Paranoid score: 8
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Firmware/RF-mediated external influence: +1. Radar detection can be influenced from the RF environment when the device operates on DFS channels.
* Generic memory corruption: +2. The bug is a slab use-after-free of `ieee80211_chanctx`.
* Real lifetime corruption: +1. `ieee80211_dfs_cac_cancel()` can remove and free the current list element while it is still being iterated.
* Reliable kernel crash / strong DoS: +1. Using a freed `chanctx` can crash or destabilize mac80211.
* Broad/default subsystem exposure: +1. mac80211 is a broadly deployed Wi-Fi stack component.
* Hard/specific condition: -1. Triggering requires DFS radar handling, relevant channel context state, and likely MLO-related setup.

Paranoid additional signals:

* Adjacent/RF reachable trigger: +1. An attacker in radio range may be able to induce radar-detection behavior without local privileges.
* Weak to strong LPE concern: +1. UAF in kernel heap object lifetime can sometimes become exploitable if object reuse is influenceable, though no concrete reclaim primitive is shown.
* Confidentiality/integrity plausible: +1. Paranoid score accounts for possible impact beyond DoS due to heap UAF.

## 3. Reachability analysis

The realistic trigger is tied to Wi-Fi DFS radar detection while the device is using DFS channels and has affected channel-context state. A remote Internet attacker cannot trigger it. An RF-adjacent attacker may be able to influence radar-detection events, but practical reliability depends on hardware, regulatory DFS behavior, MLO state, and driver support.

Local privileges are not necessarily required in the RF-adjacent scenario once the victim device is already configured on the affected channel. However, setting up the vulnerable operating state may require normal system/network configuration.

## 4. Severity interpretation

This is at least actionable Moderate and a Strong Important candidate under paranoid triage. The realistic impact is kernel crash or Wi-Fi subsystem DoS. The theoretical higher impact comes from slab UAF in mac80211 object lifetime handling.

No arbitrary write or proven exploit chain is shown, so treat LPE as a manual-review concern rather than demonstrated impact.

## 5. One-sentence report phrase

mac80211 DFS radar detection work used unsafe list iteration while CAC cancellation could free the current channel context, creating a slab use-after-free that may be RF-adjacent triggerable in DFS configurations.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

This is a kernel heap UAF in a broadly deployed Wi-Fi subsystem, with possible RF-adjacent triggering depending on DFS and device state.

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

Patch: wifi: mac80211: use safe list iteration in radar detect work
Commit: 887ece6c23b49d02a6678e7a8d5ad213d75883ce
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=887ece6c23b49d02a6678e7a8d5ad213d75883ce

Commit description:

The call to ieee80211_dfs_cac_cancel can cause the iterated chanctx to
be freed and removed from the list. Guard against this to avoid a
slab-use-after-free error.

Cc: stable@vger.kernel.org
Fixes: bca8bc0 ("wifi: mac80211: handle ieee80211_radar_detected() for MLO")
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20260505151539.236d63a1b736.I35dbb9e96a2d4a480be208770fdd99ba3b817b79@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/mac80211/util.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=887ece6c23b49d02a6678e7a8d5ad213d75883ce

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

The original Linux kernel CVE announcement for CVE-2026-46166 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46166

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:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.5

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: 6
  Paranoid ActionableScore: 8

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).