[CVE-2026-64325][MODERATE REGULAR] wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon [ Upstream

[CVE-2026-64325][MODERATE REGULAR] wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64325
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon [ Upstream
Commit: 77e7b127472a191e086e1e0b1b051703f33b1801
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77e7b127472a191e086e1e0b1b051703f33b1801
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64325
Analysis date: Sat, 25 Jul 2026 13:55:54 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline. Manual review recommended due adjacent-network kernel DoS
Manual review required: YES

Summary:
A NULL pointer dereference in mt76 mt7921 and mt7925 CSA beacon handling can be triggered from adjacent WiFi range when queued channel switch work runs after channel context teardown, causing a kernel crash and denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-64325 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64325

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-2026-64325	MODERATE	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:H';**CWE-476;CWE-362;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 'A NULL pointer dereference in the mt76 mt7921 and mt7925 CSA beacon handling path can occur because mt7921_channel_switch_rx_beacon or mt7925_channel_switch_rx_beacon may run after the station disconnects or the channel context is torn down. In that state dev new_ctx can already be NULL, but the driver dereferences it while processing the queued channel switch work, causing a kernel crash. For the CVSS the PR:N value is used for the paranoid score because an attacker does not need a local account on the victim if they can influence WiFi management traffic from adjacent radio range. The issue is not Internet reachable and should be treated as adjacent network exposure. Impact is denial of service only because the patch shows a NULL dereference and does not provide evidence of UAF, OOB access, information disclosure, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline. Manual review recommended due adjacent-network kernel DoS (with actual score 4)	YES	REMOTE OOB DANGER NULLPTR NETWORK  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline. Manual review recommended due adjacent-network kernel DoS**

## 2. Signal breakdown

Conservative signals:

* Remote reachable / network-triggerable: +2
  Trigger input is a WiFi CSA beacon, so this is not Internet remote, but it is externally triggerable from adjacent radio range.
* Reliable kernel crash / strong DoS: +1
  The report shows a NULL pointer dereference at address 0x0 in `mt7921_channel_switch_rx_beacon()`.
* Broad/default/common subsystem exposure: +1
  WiFi client operation and CSA beacon processing are normal wireless paths on affected mt76 hardware.
* Hard or unreliable race / special timing required: -1
  The crash requires `dev->new_ctx` to be cleared between queued work creation and execution.

Paranoid difference:

* Do not subtract the race penalty in the paranoid score because a malicious AP or adjacent attacker may repeatedly force CSA and disconnect or teardown timing, making the condition more practically reachable.

Not applied:

* No generic memory corruption bonus. The patch shows a NULL dereference, not UAF, OOB write, double free, type confusion, or stale object reuse.
* No privilege escalation bonus. There is no demonstrated reclaim, overwrite, callback control, or object confusion primitive.
* No confidentiality or integrity impact. The observed primitive is crash only.

## 3. Reachability analysis

An attacker does not need a local account on the victim if they can influence WiFi management traffic from adjacent radio range, for example as a malicious AP or nearby radio attacker. This is not AV:N Internet reachability, but it is realistic adjacent-network exposure for affected clients using mt7921 or mt7925 devices.

Namespaces and containers do not materially affect triggering, because the relevant input is received by the wireless stack and driver from the radio environment. The path is only present on systems with the affected MediaTek mt76 WiFi hardware and driver loaded, but no unusual debug or legacy mode is required.

Call-site confidence: high. The provided patch shows the exact dereference site and the added `dev->new_ctx` NULL guard in both affected driver callbacks.

## 4. Severity interpretation

This behaves like an actionable Moderate / borderline manual-review issue rather than Important. The practical impact is adjacent-network denial of service via kernel crash. Theoretical escalation is not supported by the patch because the failure is a NULL pointer dereference after asynchronous state teardown, with no evidence of attacker-controlled reuse or memory corruption.

The paranoid score is higher only because adjacent WiFi management traffic can be attacker-influenced and repeated, making the crash condition more plausible than a purely local hard race.

## 5. One-sentence report phrase

A NULL pointer dereference in mt76 mt7921 and mt7925 CSA beacon handling can be triggered from adjacent WiFi range when queued channel switch work runs after channel context teardown, causing a kernel crash and denial of service.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the issue is externally triggerable from adjacent WiFi range and causes a kernel crash, but the patch supports DoS only and does not show a memory corruption or privilege escalation primitive.

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

Patch: wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon [ Upstream
Commit: 77e7b127472a191e086e1e0b1b051703f33b1801
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77e7b127472a191e086e1e0b1b051703f33b1801

Changed files:
  drivers/net/wireless/mediatek/mt76/mt7921/main.c
  drivers/net/wireless/mediatek/mt76/mt7925/main.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=77e7b127472a191e086e1e0b1b051703f33b1801

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

The original Linux kernel CVE announcement for CVE-2026-64325 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64325

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: 3
  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: 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).