[CVE-2026-63832][MODERATE 7.0] wifi: mt76: add wcid publish check in mt76_sta_add

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

CVE: CVE-2026-63832
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: wifi: mt76: add wcid publish check in mt76_sta_add
Commit: 3c499851753a24d2e148d4e9ca51764c0c51554e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c499851753a24d2e148d4e9ca51764c0c51554e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63832
Analysis date: Sun, 19 Jul 2026 11:17:07 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A network-adjacent mt76/mt7925 reconnect path can reinitialize an already published wcid and corrupt kernel list metadata, causing a likely kernel crash with limited but nonzero concern for broader memory corruption.

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

The original Linux kernel CVE announcement for CVE-2026-63832 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63832

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 7.0
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-2026-63832	MODERATE	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:H/I:H/A:H';CWE-665;*CWE-787;CWE-362;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'A kernel list corruption issue in the mt76 WiFi driver can occur because mt76_sta_add may reinitialize a wcid that was already published by the mt7925 specific station add path. Reinitializing the already published object can corrupt wcid poll_list and dev sta_poll_list while RX or TX status processing is still able to observe the object, leading to list_add corruption and a possible kernel crash. For the CVSS the PR:N is used for the paranoid network-adjacent interpretation, because a nearby attacker may not need local privileges on the victim if malformed AP behavior or forced roaming can drive the affected station state. The attack is not Internet remote and requires WiFi adjacency, mt7925 or affected mt76 hardware, and a specific reconnect or station add sequence, so AC:H is appropriate. Impact is at least denial of service. Because the symptom is kernel list corruption of an already published object rather than a simple NULL pointer dereference, the worst-case assessment keeps confidentiality and integrity impact for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE DANGER INIT SIMPLEFIX NETWORK  INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Network-adjacent triggerability: +2
  The observed sequence involves WiFi disconnect, authentication to another AP, and RX/TX status processing. This is not Internet-remote, but a nearby AP or wireless environment may influence the affected reconnect path.

* Memory corruption, weak or indirect corruption candidate: +1
  The patch prevents reinitializing an already published `wcid`. The reported failure is `list_add corruption` in `dev->sta_poll_list`, but the patch does not show attacker-controlled payload, attacker-selected overwrite target, UAF reclaim, or callback control.

* Reliable kernel crash / strong DoS: +1
  Kernel list corruption in `list_add` is a credible crash or panic condition.

* Hard or unreliable timing / state dependency: -1
  Triggering appears to require mt7925 or affected mt76 hardware plus a specific station add / reconnect / RX status sequence.

* Corruption primitive constrained or metadata-only: -1
  The corrupted object is list metadata associated with an already published driver object. No direct arbitrary write or controlled data corruption primitive is shown.

Conservative total: 3

Paranoid additions:

* Weak LPE concern: +1
  Because this is kernel list corruption of a published object visible to asynchronous RX/TX paths, broader memory corruption impact cannot be fully dismissed without manual review.

* Privileged kernel/device-management corruption path: +1
  The corruption occurs inside a WiFi driver data structure used by trusted kernel RX/TX processing, even though attacker control appears indirect.

Paranoid total: 5

Call-site confidence: high. The patch, affected function, and crash trace show the relevant call path through `mt76_wcid_add_poll`, `mt7925_rx_check`, and RX polling.

## 3. Reachability analysis

A local user is not required if the issue can be driven by wireless association or roaming behavior from the environment, but this is only network-adjacent and requires proximity to the victim WiFi client. The issue is not remotely reachable over the Internet.

The affected path requires mt7925 or another affected mt76 configuration and a reconnect or station-add sequence where `wcid` was already published before `mt76_sta_add()` reinitializes it. Namespaces and containers do not materially affect reachability because the trigger is in the host WiFi driver and hardware path.

The path is default-relevant only on systems using the affected MediaTek WiFi hardware and driver. Realistic exploitation conditions exist for DoS. Exploitation beyond DoS is not demonstrated.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because the observed symptom is kernel list corruption, not just a warning or validation failure. Realistically, it behaves like a network-adjacent driver DoS requiring specific hardware and timing.

Theoretical memory corruption potential exists because an already published kernel object is reinitialized and list metadata becomes corrupted. However, the patch does not demonstrate attacker-controlled reclaim, arbitrary write, function pointer control, or a reliable privilege-escalation primitive. Therefore the conservative score remains borderline, while the paranoid score reaches Actionable Moderate and should not be auto-closed.

## 5. One-sentence report phrase

A network-adjacent mt76/mt7925 reconnect path can reinitialize an already published wcid and corrupt kernel list metadata, causing a likely kernel crash with limited but nonzero concern for broader memory corruption.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Manual review is required because the bug involves kernel list corruption in an asynchronous WiFi driver path and may be influenced by adjacent wireless behavior, even though practical privilege escalation is not proven by the patch.

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

Patch: wifi: mt76: add wcid publish check in mt76_sta_add
Commit: 3c499851753a24d2e148d4e9ca51764c0c51554e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c499851753a24d2e148d4e9ca51764c0c51554e

Commit description:

Since mt7925_mac_sta_add publishes wcid, add publish check in mt76_sta_add
to avoid reinitializing the wcid->poll_list.

Found dev->sta_poll_list corruption when using mt7925 and 7.1-rc4.
According to the corruption information, prev->next was changed to itself.

wlan0: disconnect from AP 90:fb:5d:94:8b:e3 for new auth to 90:fb:5d:94:8b:e2
wlan0: authenticate with 90:fb:5d:94:8b:e2 (local address=84:9e:56:9c:7e:6b)
wlan0: send auth to 90:fb:5d:94:8b:e2 (try 1/3)
 slab kmalloc-8k start ffff8c80958a6000 pointer offset 4160 size 8192
list_add corruption. prev->next should be next (ffff8c808a7488f8), but was ffff8c80958a7040. (prev=ffff8c80958a7040).

 mt76_wcid_add_poll+0x95/0xd0 [mt76]
 mt7925_mac_add_txs.part.0+0xa5/0xe0 [mt7925_common]
 mt7925_rx_check+0xa7/0xc0 [mt7925_common]
 mt76_dma_rx_poll+0x50d/0x790 [mt76]
 mt792x_poll_rx+0x52/0xe0 [mt792x_lib]

Signed-off-by: Jiajia Liu <liujiajia@kylinos.cn>
Link: https://patch.msgid.link/20260528033814.46418-1-liujiajia@kylinos.cn
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/wireless/mediatek/mt76/mac80211.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=3c499851753a24d2e148d4e9ca51764c0c51554e

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

The original Linux kernel CVE announcement for CVE-2026-63832 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63832

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: 3
  Paranoid ActionableScore: 5

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 7.0

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).